• Please review our updated Terms and Rules here

Compact Flash with true 8-bit XT IDE Interface

I'd like to be the first... I think that also Late Tandy machine and Amstrad PC1512 will benefit of it.
I have to Thank you for all your advice, without it (and without XTIDECF for tests) it not had be possible.
I managed also to modify the PC BIOS to include XTIDE universal Bios and i left reset line unconnected (it work After all!)
In your opinion is possible to use DMA with the XTA? (Universal BIOS does only PIO with 8 bit...)

Now i want to male a new project a "AS6C4008 512kb RAM" in your "XTIDECF". I see that swapping a couple of lines (WE# A14 A15) the pinout is to The CMOS SRAM. Then i have it mapped to C800, right? And is from C800, until? EFFF?
 
Yes, I Made it at last! I think will be useful in other XTA interface!
Now i'm trying to Use RAM AS6C4008 512k in the XTIDECF interface instead of ROM. There are only a couple of Lines swapped (WE# A14 A15) and Then i can access the RAM At C800:0000 and go on (until EFFF?), right?
I'm aiming to UMB in an XT for more free ram.
 
Interesting idea. Are you using my 'ISA CompactFlash Adapter' (this)? That will map in 32K, from C800-CFFFh. But it could be extended to 64K covering C000-CFFFh by bending out pin 8 of '688 IC3 and connecting it to Vcc (5V), and to 128K by also bending out pin 11 and connecting that to Gnd (that would cover C000-DFFFh).
 
Thank you pearce!
Yes, i'm using exactly that adapter! Thank you for you advices (as Always), i'll try until 128k
I'm aiming to have as much as I can UMB to load UP all driver, etc etc
I'm trying to replicate the following schematic:
PCRAMExtension-Schematic.jpg

It will be very interesting to have a mini adapter (like your "'ISA CompactFlash Adapter") with thru-hole component (I LIKE!) with the AS6C4008 512k (cheap and cover all the ram from 512k up to 1Mb)
Should be great to configurate it like: A000-AFFF B000-BFFF or B800-BFFF with dipswitch or jumpers (32k selection would be very good, maybe 8/10 switch)

i'm aiming to have (should be free in a plain XT)
A000-AFFF (disabled if VGA active)
B000-BFFF - DISABLED - (in some CGA may have free zone)
C000-C7FF (disabled if VGA BIOS)
C800-CFFF (disabled if XTIDE & OR large VGA BIOS)
D000-DFFF
E000-EFFF

So a max total of 256k UMB free!!!
Disable some of the area, is mandatory, right? what happen in the isa bus if I have both ROM & RAM active at the same address? (in an AT maybe is possible to have Shadow RAM)

Are you interested in building a test card (as an alternative to your 1Mb SMD card)....? ;)
 

Attachments

  • PCRAMExtension-Schematic.jpg
    PCRAMExtension-Schematic.jpg
    13.4 KB · Views: 5
Last edited:
Ok, the experiment has SUCCESS!
For 32k C800-CFFF, it worked immediately!
For 128k from C000-DFFF i had to modify '688 like you suggested but wasn't working. Examining schematics, i see that lines A15 & A16 in the ROM was connected to GND, so my ram was mapped four time and repeats @ C000, C800, D000, D800.
So at '688 (i used an additional IC socket) i tied pin P3 to Q3 & P4 to Q4 - 688 chip side - (alway on, thus A15&A16 don't care) and take A15 and A16 line (pin 8 & 11) to corresponding ROM/RAM line!

The result is: 128k Upper memory, maybe too much for a XT! Loaded all up thank to DOSMAX, i had plenty free memory (97K upper, 593K lower)... time to use some drive cache? RAM drive? :)

Thank you pearce, for all the info (and your expansion). Maybe is possible to modify your ROM card for take this into account? (some jumper to invert #WE & A15)

20141115_184035.jpg
 
Good spot re the address lines; I'd missed that. Thanks for posting back & I'm glad you've got it working.
 
Can anyone post the schematic for the cable to conect the compact flash on the olivetti prodest pc1?
Or a Picture of the lines to be cut and adressed?

Regards

JOSÉ
 
I'm looking for specific info on XTA and having trouble finding it. If someone has links to accurate pin-outs and the register description for the 4 address locations, I would appreciate it. I'm trying to add support to NetPi-IDE for XTA.
 
Thanks, I believe that's all I need - other than a XTA capable unit. I'll pick up a Tandy 1000 RL or RLX soon, but I have one I can borrow in the meantime.
 
sorry to necro thread

sorry to necro thread

Simone2013 said:
Maybe this can help:
https://www.dropbox.com/s/qtowae5u0o5b5do/IBM XT IDE registri.pdf?dl=0
Ask if you have more questions...
Click to expand...

just got a pcs86 complete motherboard and its 3x full length 8-bit isa riser, i need this file, if you can please help me. if it exists in english would be a plus.

i have all: a gotek usb floppy drive emulator, a 1.44mb standard floppy drive, a nec v30HL @ 16mhz, 2x 16mb 30pin simms (32mb of fpm?), 8-bit isa ibm 74f5175 nic card and a 8-bit isa soundblaster 2.0 cti350b. plus a combo 8/16-bit isa realtek rtg3105f 1024kb (1mb) card that should allow me the best possible video memory on this unit, a compatible psu

i need the ability to have fixed disk storage, and this thing is XTA not ATA it seems, then i found you guys, thank goodness....please help me get a xta to cf unit up and working on this pcs86...its so rare
 
You must log in or register to reply here.
Back
Top