How to read parallel-port POST diagnostic codes?

[AlG]

Thanks for the reply, and the advice help regarding the error codes.

Sounds like I'll go ahead with attempting to swap the DMA chip out. But I’m probably going to practice de-soldering a bit first. If that doesn't work I'll look at the memory.

I've got a temperature controlled soldering iron, but will still probably go for the cut the chip out and then de-solder the legs separately approach. As I’m not sure I’ll be able to get all 40 pins molten at the same time.

Alternatively I might considering picking up a cheap Hot Air re-flow gun, and following the technique outlined here:
http://hackaday.com/2016/01/12/desolder-dip-packages-like-a-pro/
But I’m not sure how well it would work on a 40-pin IC. Although the video makes it look very easy to de-solder memory chips.


I'll also probably remove the leaky battery at the same time, especially since there are concerns about it's affect on the motherboard. I'm assuming the system should run fine without a battery, until I can get round to replacing it.

 

[1ST1]

Additionally to the solder iron you must have a desoldering pump. Also a needle fixed at the end of a chopstick (the wodden sticks chinese peoples use instead of fork/knife) is usefull. With that you can feel and hear if a pin is well desoldered.

 

[T-R-A]

As I’m not sure I’ll be able to get all 40 pins molten at the same time.

You won't. If you don't have something like a desoldering station or desoldering pump (Google both if you're not certain), then use your method of cutting the legs (close to the body) and pulling each out as you reheat them. You'll need to clean the holes before inserting the new chip and re-soldering.

 

[alecv]

Sorry for offtopic.

Does anyone have a XT BIOS or Testing ROM sourcecode with LPT or 0x80 diagnostic output ? AFAIK, IBM XT original BIOS (available in sources) does output to port 0x60 but diagnostic code points are very "coarse". I did not find XT BIOS sourcecode with 'modern style' output to port 0x80. I have a dead XT board, it initializes PIT and DMAC (I see a correct DMA0 pulses for DRAM regeneration) but hangs before first 64K test and video initialization.

 

[modem7]

Does anyone have a XT BIOS or Testing ROM sourcecode with LPT or 0x80 diagnostic output ? AFAIK, IBM XT original BIOS (available in sources) does output to port 0x60 but diagnostic code points are very "coarse". I did not find XT BIOS sourcecode with 'modern style' output to port 0x80. I have a dead XT board, it initializes PIT and DMAC (I see a correct DMA0 pulses for DRAM regeneration) but hangs before first 64K test and video initialization.

Are the Supersoft/Landmark Diagnostic ROMs [here] not suitable for you ?

 

[AmigaJules]

I've finally been able to get back to this project.

It looks like the PSU in my 6300 is indeed on its way out and may have been the cause of my problems, instead of the battery leakage. I've hacked up a Dell PSU to give me the +5, +12 and -12 volt outputs.

I have 2 6300 motherboards, one with ROM 1.21 and the other with 1.43. On the 1.21 the LPT code reader outputs a 43 then a 45 and the previous/next buttons don't do anything.

On the 1.43 I see 43, 44, 45, 48, A5, 3F. Using the prev/next buttons I can cycle between the last 3 codes 48, A5, 3F. That's good news based on the codes listed in an earlier comment.

I'm going to connect the hacked PSU a little more securely, then replace the EGA video card and keyboard and see if I get any output on the display.

 

[AmigaJules]

Progress??

I installed the EGA card and keyboard and fired it up.



For. Exactly. One. Boot....

Subsequent restarts give me code 43, 44, 45, keyboard lights keep flashing, nothing on the display.

So if I understand the codes from previous posts correctly:
On the 1.21 ROM motherboard since it display 43 and 45 without displaying 44 - the first 64K RAM may be bad?
Any hints on what to look for if it stops at 45 on the 1.43?

 

[Trixter]

I'm confused; you said EGA card, but I see the AT&T monitor in your screenshot. What EGA card do you have? Was the monitor hooked up to it? What happens if you connect it to the regular 6300 display card?

I don't have the 1.21 ROM BIOS so I haven't disassembled it to see if/why/how it skips 44h, sorry.

For the 1.43 board, the very next stop after outputting 45h is initializing the video and printing a message:

seg000:DD55                i_pic_ok:                               ; CODE XREF: seg000:DD1Aj
seg000:DD55 B0 45                          mov     al, 45h ; 'E'   ; Checkpoint #5
seg000:DD57 BA 78 03                       mov     dx, 378h
seg000:DD5A EE                             out     dx, al          ; Printer Data Latch:
seg000:DD5A                                                        ; send byte to printer
seg000:DD5B
seg000:DD5B                i_pic_end:                              ; CODE XREF: seg000:DD4Dj
seg000:DD5B BC 00 01                       mov     sp, 100h
seg000:DD5E E8 AE 03                       call    i_vector        ; Install Vector Table
seg000:DD61 E8 FA 02                       call    i_d_init        ; Determine System Configuration from Switches and Initialize Video.
seg000:DD64 B4 0F                          mov     ah, 0Fh
seg000:DD66 CD 10                          int     10h             ; - VIDEO - GET CURRENT VIDEO MODE
seg000:DD66                                                        ; Return: AH = number of columns on screen
seg000:DD66                                                        ; AL = current video mode
seg000:DD66                                                        ; BH = current active display page
seg000:DD68 32 E4                          xor     ah, ah
seg000:DD6A CD 10                          int     10h             ; - VIDEO - SET VIDEO MODE
seg000:DD6A                                                        ; AL = mode
seg000:DD6C BE CA D9                       mov     si, offset aResidentDiagno ; "Resident Diagnostics\r\nRev 1.43\r\n\n"
seg000:DD6F E8 88 02                       call    DRomString

So if it outputs 45h and then you see nothing, it couldn't set the video mode and print the "Resident Diagnostics" message. (That's why I asked you about the EGA card.)

 

[1ST1]

Plese note that for add on graphics card the internal graphics card of M24/6300 has to be modified (remove a gal and bridge it). If you plugin a graphics card in M24 with unmodified internal graphics card you damage the machine! If you startup modified M24/6300 without add on graphics card, it won't boot.

As far as I remember you can find the description how to modify the graphics card on the 6300 shrine website. Trixter, you should have the description from my upload.

 

[Trixter]

The 1.43 ROM BIOS kit came with two PALs/GALs, I thought?

 

[1ST1]

If you replace old BIOS with 1.43 no modification/gal/pal neccessary. Addon graphics needs modification. Without modifacation, add on graphics card will destroy M24/6300. Is that clear enough?

 

[Trixter]

As far as I remember you can find the description how to modify the graphics card on the 6300 shrine website. Trixter, you should have the description from my upload.

I was only able to find https://sites.google.com/site/att6300shrine/tutorials/disable-video-card and nothing else...?

If you replace old BIOS with 1.43 no modification/gal/pal neccessary. Addon graphics needs modification. Without modifacation, add on graphics card will destroy M24/6300. Is that clear enough?

No, you've made it more confusing, as you stated no modification necessary, then needs modification.

For the exact case of a 1.43 BIOS, and the DIP switches set accordingly (EGA/onboard video disabled: SW5--On SW6--On), is that enough to add a card? Or are you saying all systems need a hardware modification? (The URL I referenced shows a 1.43 BIOS working without additional modification)

 

[AlG]

Welcome to the forums!

The good news is that your board is booting up past the parallel-port POST codes and getting to the part where it can actually display errors onscreen (you probably won't need the LPT POST device). The bad news is that the error message onscreen is very likely what the actual problem is: Either your DMA controller chip needs replacement, or the first 64KB of RAM on your motherboard needs replacement (the DMA test uses the first 64K of RAM to do its testing). Either way, you're going to have to fire up the soldering iron. The "suberror" for RAM failure during the test is 04, but yours is reporting 01 so I think you need to replace your DMA controller chip.

It is ok and safe to use a 6300 keyboard with your M24; that hardware should be identical and only differ in terms of branding. A 6300 system unit and an M24 system unit are also identical except for the BIOS contents (and PAL chips that are paired with the BIOS).

I just wanted to post an update on my issue. I've got rid of the "DMA Control Fail:01" error.
You were correct that the DMA controller chip needed replacing. I've done this and my M24 boots fully into DOS 3.3.
I didn't need the parallel code reader after all.



Before starting the swap out, I checked the DMA pinout and confirmed my existing controller was getting the expected voltage. This is about the limit of electrical tests I can perform with my equipment.

In regards to the soldering, it is tricky if you're a novice like myself, but it is do-able.

Whilst I am a novice, I found the following useful (this is what worked for me).

- Using a temperature controlled soldering station with a suitable sized chisel tip (375 degrees C for desoldering and 350C for soldering). I picked up a cheap Yihua 936 unit and additional tips (don't use the provided conical tip).

- I chopped off the legs and de-soldered them separately. When doing this I put the iron on the remains of the leg and was able to lift most of the legs out without tweezers. Most of them adhered to the iron enough to lift them out, as long as the iron had some solder on it. But you’ll probably need tweezers for a few.

- To clear the through holes of solder I used freshly purchased (Chemtronics) solder-wick, any good brand should do. This was purchased through a known supplier as apparently there is lots of counterfeit solder wick (not all wick is created equal and old wick is less affective). I used just over a roll, so make sure you purchase enough, and ensure it’s not too wide. I tried a solder ‘sucker’ pump, but it didn’t work well for me (probably just personal preference)

- I used a quality turned pin IC socket, and was careful not to use to much solder when installing the socket.


I watched lots of youtube videos to get an idea of how to do things at each stage and took my time.

Thanks again for the advice; I’ll probably post my own thread at some point, when investigating some other issues the machine is having (like write errors to the hard-disk when copying from the floppy).

Thanks,

- Alastair


Now I just need to get a mouse ...

 

[1ST1]

Cool, congratulations!

 

[Trixter]

This is wonderful, excellent advice! I am in exactly the same boat, with the same amount of soldering experience, and with a 40-pin IC to replace on my board to fix it (also the 8237a). I hope to repeat your success when I'm more comfortable with my skills!

As for a mouse, there's one on ebay right now for a fair price...

 

[1ST1]

This is the real 6300 mouse. I have two of the same with Olivetti logo for M24. Please note that this one is connected to the 6300 keyboard. It's having similar signals as Amiga/ST/Euro-PC/Prodest-PC1, it's even possible using their mouses on M24/6300 with adapter, or vice versa M24/6300 mouse on these computers. It's not a serial mouse. And not all keyboard models (for M24) do have this connector.

 

[AlG]

In regards to the mouse, I've noticed in the manual that the keyboard ROM must be at least v1.1 to support the mouse. Is there any way to check what version my keyboard ROM is?. I’ve opened the keyboard up, but didn’t seem any numbers on the chip I assume is the ROM.
I would like to get a genuine Olivetti/AT&T mouse, but I don't want to buy if it won't work with my keyboard.

I'm also coming to the conclusion that my hard disk is somewhat unhappy, as I'm getting write errors when I create new files/directories.
I need to pop the lid of the unit and check what model the HDD is. It's an all in one ISA card, with the drive being a 3.5" unit mounted on the card, I'll try and get some more information on it. Is there any specific hardware diagnostic software that is useful for these machines?

I’ve got a copy of the customer diagnostic tool (1.03a). Do any of you have a working image of a later version? All the copies I’ve found online of later versions appear to be corrupt disk images. I'm wary of running this as it seems a very early piece of software.

I do remember it had hard disk issues when I used it last (some years back), but back then they stopped once the machine had been running a few minutes. Now they happen no matter how long the machine has been switched on.


Thanks,

- Al

 

[Trixter]

In regards to the mouse, I've noticed in the manual that the keyboard ROM must be at least v1.1 to support the mouse. Is there any way to check what version my keyboard ROM is?. I’ve opened the keyboard up, but didn’t seem any numbers on the chip I assume is the ROM.
I would like to get a genuine Olivetti/AT&T mouse, but I don't want to buy if it won't work with my keyboard.

I don't know of a way, other than visually inspecting the ROM, to determine what version it is. Since you have the 1.43 BIOS and a 6300 keyboard (later model of keyboard than the M24 keyboard), I wouldn't worry. I've had three different 6300 setups and I never once had a problem connecting the 6300 mouse.

The 6300 mouse has an interesting property in that it emulates keypresses with no mouse driver loaded, which means you can use it with software that doesn't support mice. There's a video of this in action, if you want to see how it works for yourself and determine if the 6300 mouse is something you want.

I'm also coming to the conclusion that my hard disk is somewhat unhappy, as I'm getting write errors when I create new files/directories.
I need to pop the lid of the unit and check what model the HDD is. It's an all in one ISA card, with the drive being a 3.5" unit mounted on the card, I'll try and get some more information on it. Is there any specific hardware diagnostic software that is useful for these machines?

The customer diagnostics are the best for determining what is wrong with a 6300 or M24.

That's not the stock 6300 hard drive, so the 6300 low-level format tools aren't appropriate to use with it. A quick'n'cheezy way to reformat the drive in-place, locking out bad areas, is to run spinrite 5.0 or lower on the drive (2.0 is probably preferable) and have it check for errors.

I’ve got a copy of the customer diagnostic tool (1.03a). Do any of you have a working image of a later version? All the copies I’ve found online of later versions appear to be corrupt disk images.

Have you tried the 6300 shrine? https://sites.google.com/site/att6300shrine/Home/downloads
I personally uploaded almost everything there. The AT&T DOS 3.2 distribution archive contains a later version of the customer diagnostics.

There's one wrinkle: You don't actually have a 6300, but rather an M24. They are *supposed* to be identical, but I've never owned an M24 and run the 6300 diags on them. YMMV.

I'm wary of running this as it seems a very early piece of software.

I don't understand what that means. All of these are "very early pieces of software".

 

[AlG]

Hi,

Sorry I should have explained, I was wary of the early diagnostics as it identifies my hard disk as 10MB, when I know it to be 20MB. Since my machine was manufactured a couple of years after the date of the early diagnostics I thought I may require a later version. However the hard-disk being non-standard probably explains why the diagnostics didn’t identify it correctly.

It's a 20MB Miniscribe 8425. The disk is from 1989, when my machine dates from 1986 so I imagine it was an after market upgrade. When it fails to write date it makes a grinding noise, which is noticeably different from normal operation. This mainly happens when I try to write new files. Hopefully it’s just some bad sectors that can be marked and avoided.

I’m having issues getting spinrite to work, as it hangs before properly loading. I’ll try another version and let you know how I get on.

I’ve tried the dos 3.2 images you mention (thanks for uploading them), but the customer diagnostic disk appears empty when I open it with WinImage (the other disks are OK). Is there some other disk image software I should be using?

Thanks,

Alastair

 

[Trixter]

I’m having issues getting spinrite to work, as it hangs before properly loading. I’ll try another version and let you know how I get on.

If using Spinrite 5.0, it requires DOS 6.22 to work reliably on an 8088-class system. (When I try with later versions, like PC DOS 7.0, it hangs in the memory testing phase.) Spinrite 2.0 interfaces with MFM controllers at a low level, so it is a better choice than 5.0 for your hardware.

I’ve tried the dos 3.2 images you mention (thanks for uploading them), but the customer diagnostic disk appears empty when I open it with WinImage (the other disks are OK). Is there some other disk image software I should be using?

It is a bootable disk, so you should just write it to a disk using rawrite (modern system) or img2dsk (DOS) or something. WinImage is confused by the filesystem structure on that disk which is why it doesn't display anything, but the image is valid.