BLITTER IN A ST - FPGA

[Cyprian]

just to clarify, this topic is related to FPGA BLiTTER https://www.exxosforum.co.uk/forum/viewt ... &t=79#p205
Which can be programmed as a pure BLiTTER replacement or CPU+BLiTTER (this is covered by my "crazy idea")

I have a crazy idea.
As the BLiTTER (left) has almost the same pinout as 68000 (right), would be possible to add missing pins?
It would allow to extend functionality by cpu emulation like Ijor's FX Cast or T68k with its ultra speed.

CPU_BLiTTER.png (38.62 KiB) Viewed 5295 times

[exxos]

I have a crazy idea.
As the BLiTTER (left) has almost the same pinout as 68000 (right), would be possible to add missing pins?
It would allow to extend functionality by cpu emulation like Ijor's FX Cast or T68k with its ultra speed.

Add missing pins to what exactly ? The blitter and CPU have totally different pinouts and pins.. You can pretty much link all the address & databus from the blitter to the CPU, but you also have to re-route the BGI,BGO pins from GLUE to the blitter as well, because those solder jumpers which are normally on the STFM etc are not on the ST, so you have to also re-route a couple pins on the GLUE as well.

[Cyprian]

The blitter and CPU have totally different pinouts and pins

look the screenshot above, the pinout is almost the same.
difference is e.g.: the BLiTTER site: lack of IPL signals; doubled pins for bus granting (one set for MMU, the other for CPU) etc.

[exxos]

look the screenshot above, the pinout is almost the same.
difference is e.g.: the BLiTTER site: lack of IPL signals; doubled pins for bus granting (one set for MMU, the other for CPU) etc.

The pinout is totally different, just look at the numbering on the chips..

You need a adapter PCB with the blitter pinout and wire it up to the CPU pinout..

[Cyprian]

The pinout is totally different, just look at the numbering on the chips..

You need a adapter PCB with the blitter pinout and wire it up to the CPU pinout..

ok, you mean the order of pins. sorry my english isn't perfect.
the pin order is different but functionality of those pins is the same, besides small changes mentioned earlier.
my crazy idea was to adopt that fpga blitter to: 1) the cpu slot pinout; 2) fully compatible pins funcionalities.
And use that fpga in all ST(f/m/e) line.

[PhilC]

My first step would be to design a blitter breakout pcb, so that all the pins are available easily and you're not just soldering to the back of a socket.

Of course you could incorporate a cpu adaptor into this for data lines etc.

The longer you plan, the easier itll be

[Cyprian]

[Icky]

My first step would be to design a blitter breakout pcb, so that all the pins are available easily and you're not just soldering to the back of a socket.

Of course you could incorporate a cpu adaptor into this for data lines etc.

The longer you plan, the easier itll be

I agree - planning is key but expect to have failures as even the best planning can not cover everything. I have had many failures with board design and it takes a few iterations to get things right. e.g. the IDE DEV Board was the closest to working first time but we still needed to patch the board.

[Cyprian]

Got it!

Artik-wroc, my colleague from Atari.org.pl forum, sent me an article from ST-Computer Issue form November 1988:
http://www.stcarchiv.de/stc1988/11/blit ... achruesten
and screenshot below.
Based on them, some years ago he did BLiTTER's daughterboard for short ST.

ST BLiTTER

bliter[1].JPG (370.69 KiB) Viewed 5067 times

[PaulJ]

just to clarify, this topic is related to FPGA BLiTTER https://www.exxosforum.co.uk/forum/viewt ... &t=79#p205
Which can be programmed as a pure BLiTTER replacement or CPU+BLiTTER (this is covered by my "crazy idea")

I have a crazy idea.
As the BLiTTER (left) has almost the same pinout as 68000 (right), would be possible to add missing pins?
It would allow to extend functionality by cpu emulation like Ijor's FX Cast or T68k with its ultra speed.
CPU_BLiTTER.png

I can understand why one wants a glitter but there are ST's that have a spot to populate a glitter, Exxos would most likely know the board part number. It would be a lot easier getting a board that has the spot for a glitter that attempting to add one.