Search found 445 matches
- Thu Jan 26, 2023 2:38 pm
- Forum: Hardware
- Topic: "what-if" QL extended graphics
- Replies: 45
- Views: 11545
Re: "what-if" QL extended graphics
Here's a little hint that might be useful: The QL memory map has an informal unassigned area of 16k right 'under' the bottom of the screen 0 RAM. Originally the on-board IO for the QL has been documented as residing in a 64k block of addresses starting at $10000, however, if one looks at what addres...
- Wed Jan 11, 2023 11:17 am
- Forum: Hardware
- Topic: Gold Card byte-wide read access
- Replies: 5
- Views: 933
Re: Gold Card byte-wide read access
Unfortunately I don't have a GC, but I do remember there were several revisions of the INGOT for the GC, maybe that's the reason?
- Sat Dec 24, 2022 11:42 pm
- Forum: Hardware
- Topic: CPLD replacement for ZX8301
- Replies: 230
- Views: 55604
Re: CPLD replacement for ZX8301
Maybe this has been addressed before but does your implementation uses the same pixel/memory layout as the 16 colour Aurora mode ? François No, this is based on regular mode 8 except the original flash bit is used as a brightness bit. It means that for each pixel, two bits out of four are in the ev...
- Mon Dec 05, 2022 3:05 pm
- Forum: Hardware
- Topic: QL Power Supply Primary Winding
- Replies: 8
- Views: 1083
- Fri Oct 28, 2022 1:02 pm
- Forum: Hardware
- Topic: CPLD replacement for ZX8301
- Replies: 230
- Views: 55604
Re: CPLD replacement for ZX8301
Excellent work Leon! The black version looks better to me. The reason why composite will look bad is that the patterning produces a 2.5MHz frequency component which is not well filtered in the PAL coding process (Sinclair used a simplified circuit for the PAL modulation chip which does not filter ch...
- Sun Oct 23, 2022 8:44 pm
- Forum: Hardware
- Topic: CPLD replacement for ZX8301
- Replies: 230
- Views: 55604
Re: CPLD replacement for ZX8301
The extra resistors should be connected to the voltage divider before the series capacitor connected between it and the actual RGB pins of the PAL chip. The extra resistor should be connected to the common point of the 8.2k resistor from the RGB signals and 1k resistor to ground, as well as the afor...
- Mon Aug 08, 2022 3:57 pm
- Forum: Hardware
- Topic: CPLD replacement for ZX8301
- Replies: 230
- Views: 55604
Re: CPLD replacement for ZX8301
AFAIK the ATF1508AS can be used in place of EPM7128S (as used here ). But at about the same price (ATF1508 is largest in range). ATF1508S can also be had in a TQFP100 package which is small and thin, so much so that with a multilayer PCB it may be possible to squeeze the whole board within the outl...
- Sat Jul 02, 2022 12:34 am
- Forum: Hardware
- Topic: CPLD replacement for ZX8301
- Replies: 230
- Views: 55604
Re: CPLD replacement for ZX8301
Checked, mine is the old CLA2310 in a ceramic case, so perhaps one of the first ones...
- Fri Jul 01, 2022 3:03 pm
- Forum: Hardware
- Topic: CPLD replacement for ZX8301
- Replies: 230
- Views: 55604
Re: CPLD replacement for ZX8301
What do you think about the big differences of the 2 ULA speeds ? Not sure, obviously some optimization was done, the difference in the required logic is very small. It makes sense that a small mask correction could be done between batches. That being said, I only have one type (will have a look an...
- Wed Jun 29, 2022 2:01 am
- Forum: Hardware
- Topic: CPLD replacement for ZX8301
- Replies: 230
- Views: 55604
Re: CPLD replacement for ZX8301
It is difficult to test the RAM speed with that simple program because most of the code executed runs in ROM. But you could for instance do a loop of scrolling the entire screen vertically, and then subtract the time an empty loop of the same length takes. This will still have lots of cycles in ROM ...