GENDON3 improved character generator for the Model I Discussion

[TRS-Ian]

I found that one of my machines has both a Donmon 2.3 and a Gendon3 in it.

This discussion focuses on the GENDON3.

I have ripped the code from the 2716 Eprom and you can download it here: http://ianmav.customer.netspace.net.au/downloads/GenDon3-9E.bin

This is how it looks installed in the computer:



And here are some screen shots (Don's details have been covered over for privacy reasons):



Notice it has proper looking lowercase descenders (check the 'y' in 'by' and 'System'), and a better looking comma.

I'm looking into the feasibility of bringing this product back from the past, along with Donmon 2.3

Discuss.

Ian.

 

[ldkraemer]

Ian,
This is VERY INTERESTING! I've never heard of that Monitor that lives at 0x3000-0x37DF. Do you have more information
about exactly what each command does? Like "TEST", what does it do? Also ASCII, will it give a Better view of all the
ASCII Characters contained in GENDON3.BIN?

I've downloaded the GENDON3.BIN file and will run it through my scripts and see if I can extract the the ASCII (& HEX) values
of each Character in the EPROM. I'm curious if the 2716 contains two character sets, selectable by one strapped address line?
It does have enough room available for that.

Also, can you provide the wiring information from each Pin of the Original Character Generator Socket to each Pin of the
2716. I assume it's not a standard wiring so that the eight Rows of each character cell are sequential in the Binary File.
Most of the Lowercase ROM's, EPROM's, and such have the Rows at (Address, Address+0x200, Address+0x100,
Address+0x300, Address+1, Address+0x201, Address+0x101, Address+0x301, Address+2, etc). This makes it hard
to decode as only certain bits of each byte are used, and their order is jumbled.

I've always wondered why there wasn't a Monitor available for the TRS-80's.

THANKS.

Larry

 

[Hans01]

@Ian, Larry.

Most interesting, but one small problem.
These address space is used and decoded by the Quinnterface. /12288

 

[pengak]

generator character is wrong model? right>?

 

[Audronic]

Hi Larry

I have just found some info on Gendon3 (3 different dumps)

https://www.dropbox.com/s/huirzdxvb...les (3 Versions) Don McKenzie Part 1.zip?dl=0

Ray

 

[Tibs]

It also would break some other things, I think MIRE/MISE use that area too and I've seen other things use it.

If we could pick a different region it might be more viable.

 

[ldkraemer]

I took a look at the bits in the .BIN file Ian posted.

I can see these, plus some oddball bits in the right columns that don't look correct.



Are these the same in the Model 1?


Larry

 

[ldkraemer]

Ian,
I'm thinking that your EPROM read was corrupt as the following characters have several missing bits:

X
00001
10001
01010
00100
01010
10001
10001
00000

Y
00001
10001
01010
00100
00100
00100
00100
00000

Z
00001
00001
00010
00100
01000
10000
11111
00000

Larry

 

[Petrofsky]

I agree with Larry. Ian seems to have a corrupted version of the "9E" dump in the collection Audronic posted. Below are renderings of Ian's dump; the "(J.R.) 6A", "Dash 61", and "9E" dumps; and a Radio Shack lower-case chip, part 8046673.



Is there some way I'm missing to post images here without them getting heavily crappified like that? These are simple 2.5 kbyte crystal-clear 798-by-742 PNG files that the site is insisting on mangling into blurry 265x246 JPEG monstrosities that use 10 times as much storage. What the hell does the forum software think it's accomplishing?

Anyway, here are those images as externally hosted at imgur.com (until the inevitable day when imgur.com suddenly disappears):

 

[TRS-Ian]

Well spotted. I burned this dump to another 2716 and it displays corruption.

I need some help here...

Whats the best way to read the contents of the Gendon3 "4.6" 2716? I am using a G540 programmer to read the contents, then when I do a verify it says error.

When I put the Gendon3 back in the computer it reads perfect so I am 99% what is on the original chip is not corrupted.

Also, do people want me to start another thread on the Donmon 2.3 to separate out the two products?

Ian.

 

[Audronic]

Hi Ian

I had to read the Eprom in the spare socket on the System-80 (Z13) Thanks to Andrew Quinn Pointing me in this direction, Thanks Andrew.
Take a dump under newdos and remove some bytes at the start xxxxx/CIM file
I was unable to read the same eprom on a G540 also

Ray

 

[Audronic]

Hi Ian et All

A Link to some Gendon info

https://www.dropbox.com/s/mbud8mszoyubc7j/GenDon3 Info.pdf?dl=0

Ray

 

[David_M]

Last time I talked to Don he was still in Tullamarine, from memory he was retired and one of his kids was running the business.
If you are going to redo his project it might be worth talking to him.

https://www.shop-dontronics.com/

Edit: Verify errors like you describe are usually caused by oxidation on the IC legs. The IC works in circuit because the socket contacts the wide faces of the legs, your programmers zif socket makes contact with the narrower side edges of the legs.
Quick and dirty solution, press the eprom into a cheap dual wipe socket and put the eprom and socket into the zif socket of your programmer. The socket makes contact with the clean working edges of the eprom legs and offers a clean edge to the zif socket in the programmer.

Well spotted. I burned this dump to another 2716 and it displays corruption.

I need some help here...

Whats the best way to read the contents of the Gendon3 "4.6" 2716? I am using a G540 programmer to read the contents, then when I do a verify it says error.

When I put the Gendon3 back in the computer it reads perfect so I am 99% what is on the original chip is not corrupted.

Also, do people want me to start another thread on the Donmon 2.3 to separate out the two products?

Ian.

 

[TRS-Ian]

I visited Don back in '13 when I was just starting to sell the FreHD. He was doing well and still running his business from home.

All his TRS-80 information and products and data sheets on it have long since disappeared. Sad but you can't keep everything and this is my chance to bring back some of his more popular products back from the dead.

I've looked at the three Gendon3 character sets above and I can't tell the difference. If someone can please let me know what the difference between Dash-61, 6A, and 9E.

Just now I burned 9E to a 2716 and installed it in the system, works great. Removing the corrupt BIN from my site and replacing it with 9E.

Ian.

 

[Gazza]

Ian
Somewhere on the dead desktop is a copy of the Micro-80 lower case eprom.
If I can extract it from the hard drive I'll send you a copy
Gazza

 

[jaquinn]

@Ian, Larry.

Most interesting, but one small problem.
These address space is used and decoded by the Quinnterface. /12288

You are right that the ROM socket on the Quinnterface maps to this block. The boards that Ian provides include a simple ROM that tests the memory and FreHD connection but that isn't required to use/boot the Quinnterface. The idea was that after the initial setup you could pull it out and replace it with something limit this monitor.

 

[Petrofsky]

I've looked at the three Gendon3 character sets above and I can't tell the difference. If someone can please let me know what the difference between Dash-61, 6A, and 9E.

It's easier to see the differences if you open the following links in different tabs, switch between them, and look for the few pixels that change: (J.R.) 6A, 9E, Dash 61

The "(J.R.) 6A" has differences in the characters ' , ; V j m. The three punctuation marks are too far to the right, and the semicolon appears to be missing a pixel.

The only difference between 9E and Dash 61 is that Dash 61 has a real underscore at the ASCII underscore code (95), where 9E has a four-line-high lump. They both have the lump at code 31.

I would suggest going with Dash 61 with the real underscore, for better ASCII compatibility.

(I would also recommend it for the very obscure reason that the underscore character has useful properties if you're writing the user-assisted synchronization routine for a gp2000-style beam-hacking program for the Model I. Namely, it's the only character that: (1) has all its pixels on a single line; and (2) is the same in all Radio Shack character generators (and the Dash 61 generator).)

 

[TRS-Ian]

Ok here is a picture of the underside of the Gendon:



The purple wire goes to Z12p11 and the grey wire goes to Z10p14

Dash-61 looks like the best set for most applications. Thanks for pointing out the differences.

Cheers,

Ian.

 

[David_M]

If you are keen to resurrect some of Don's projects, I have a copy of the DonMon 2.3 ROM and the Boot ROM on my hard disk and I think that the pcb is installed in a model 1 that is somewhere out in the back shed.

I also have the circuit diagram and installation instructions and notes for his SpeedDon mod. It has notes for the System80, trs80 and jap trs80 as well as additional mods for the LNW expansion, TRS80 old and new expansion and the system 80 old and new expansion interfaces. The speed board can run at speeds up to 5.32MHz. I mention the speed mod because it's speed switching is supported by the DonMon ROM.

I have one of Don's old market place newsletters from Dec 1983. Based on what I see in that therew were two versions of the Gendon board, a rectangular board for the system80 and the odd shaped one you have for the model 1. He used to sell the eprom for $12.90 and the circuit board for $18.90

I visited Don back in '13 when I was just starting to sell the FreHD. He was doing well and still running his business from home.

All his TRS-80 information and products and data sheets on it have long since disappeared. Sad but you can't keep everything and this is my chance to bring back some of his more popular products back from the dead.

I've looked at the three Gendon3 character sets above and I can't tell the difference. If someone can please let me know what the difference between Dash-61, 6A, and 9E.

Just now I burned 9E to a 2716 and installed it in the system, works great. Removing the corrupt BIN from my site and replacing it with 9E.

Ian.

 

[ldkraemer]

Petrofsky & Ian,
That brings up an interesting question of how you will prepare the 6 x 12 Grid Characters to fit in the 5 x 8 that the Model 1 has.
The Left most column can be deleted, and the bottom row for the Underline (95) can be the 8th row, but that still leaves the lowercase
descenders that will have to be moved up. And then there are several that will either need to be shrunk or somehow modified to
fit and look descent & similar.

What are your ideas and suggestions?

Also since the EPROM is a 2K x 8 why not make the Character set fit in the first half, leaving the second half for a second optional
choice?

Thanks.

Larry