Search found 443 matches

by Nasta
Thu Nov 22, 2018 3:01 pm
Forum: Hardware
Topic: SGC successor brainstorming
Replies: 89
Views: 40627

Re: SGC successor brainstorming

The situation is somewhat better using more modern, or I should say, less old :P DRAM chips with faster access time (60ns), but a back-of-the-envelope calculation says it would slow down DRAM access by about 20-30% which is rather bad just to get the old stuff. Okay let's do a two-line forum calcul...
by Nasta
Thu Nov 22, 2018 2:18 am
Forum: Hardware
Topic: Hardware detectives for FrankenQL?
Replies: 22
Views: 8843

Re: Hardware detectives for FrankenQL?

Yes please! :)
by Nasta
Thu Nov 22, 2018 2:16 am
Forum: Hardware
Topic: SGC successor brainstorming
Replies: 89
Views: 40627

Re: SGC successor brainstorming

Oh, BTW just recently I found out someone made expansion video cards for the Atari ST line of computers using older VGA chips. I looked at several and found a promising one from Cirrus Logic, of course today it is long obsolete, but can still be found for a fairly decent price. It is possible to imp...
by Nasta
Thu Nov 22, 2018 2:02 am
Forum: Hardware
Topic: SGC successor brainstorming
Replies: 89
Views: 40627

Re: SGC successor brainstorming

Adding graphics means replacing the CPLD with a FPGA. Even with a fairly large CPLD extra video RAM would be needed to implement QL graphics BUT using standard VESA timing, using existing DRAM would cripple the 68020. I was under the first impression that 512x256x2 bit would still be okay with DRAM...
by Nasta
Wed Nov 21, 2018 6:18 pm
Forum: Hardware
Topic: Hardware detectives for FrankenQL?
Replies: 22
Views: 8843

Re: Hardware detectives for FrankenQL?

It is a 'built in' mod to get 512k, which is why the original 64k x 1 DRAM pins have been replaced with 256k x 1, so it needs one more multiplexed address lines. I would be VERY interested in the way this was implemented because I don't see how it can reliably refresh the RAM...
by Nasta
Wed Nov 21, 2018 12:00 pm
Forum: Hardware
Topic: SGC successor brainstorming
Replies: 89
Views: 40627

Re: SGC successor brainstorming

This requires a complete re-design, so no cloning. Tetroids latest work was more a redesign than a clone already! My thought was, that he might need/want to replace the "INGOT" PLD anyway, sooner or later. At this point, adding simple graphics could make sense for him. I personally would ...
by Nasta
Tue Nov 20, 2018 2:12 am
Forum: Hardware
Topic: SGC successor brainstorming
Replies: 89
Views: 40627

Re: SGC successor brainstorming

A few answers on Nasta's nice long post. Wish I had the time for more. Currently 1a + 2a is covered with the Tetroid SGC clone. The problem here is the Ingot CPLD which is becoming impossible to find and to a lesser extent the floppy controller chip. Even under the assumption CPLDs can be sourced, ...
by Nasta
Sun Nov 18, 2018 10:59 am
Forum: Hardware
Topic: SGC successor brainstorming
Replies: 89
Views: 40627

Re: SGC successor brainstorming

..Maybe this is being looked at from the wrong direction? Maybe we should thing in reverse and think of the original QL as a peripheral to a new single-board computer which fits within the expansion slot? It sounds like it's possibly a simpler solution to all the bottlenecks of the original system....
by Nasta
Sun Nov 18, 2018 1:01 am
Forum: Hardware
Topic: SGC successor brainstorming
Replies: 89
Views: 40627

Re: SGC successor brainstorming

May I chime in? What I see regarding hardware are two big questions that have to be answered: 1a) Keep the old case and with it the format of expansion boards, or make a true motherboard replacement OR 1b) Move to a new form factor such as ITX or similar 2a) Design using off the shelf CPU plus relev...
by Nasta
Mon Nov 12, 2018 11:21 pm
Forum: Hardware
Topic: Possible problem with cloned SGC and Minerva 1.98
Replies: 55
Views: 21906

Re: Possible problem with cloned SGC and Minerva 1.98

Just a thought - SGC uses a 68020 while GC uses a 68000, maybe it should be tested to see if there is a difference in behavior.
The 68020 has a third stack pointer for interrupts and other differences in stack frames so this may be the difference that breaks the code?