| Author |
Message |
Forum: Hardware Topic: Project Snail: 65C02 Crawling At 62.5kHz |
| Sheep64 |
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Posted: Wed Jun 01, 2022 4:41 pm
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Replies: 13
Views: 4427
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| ... a marginal use of resources. Superior address decode fits on one 5cm*7cm perfboard. Asymmetric clock fits on the same perfboard. So, for a while, XR2600 Series is going to be a one circle, one rectangle implementation. Even if my work had no error, a board received in Jan 2022 would require bodging ... |
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Forum: Hardware Topic: Project Snail: 65C02 Crawling At 62.5kHz |
| Sheep64 |
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Posted: Thu May 26, 2022 12:48 pm
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Replies: 13
Views: 4427
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| ... If contiguous memory is unimportant, this arrangement is also compatible with the 74x157 hack to obtain fast 20 bit or 24 bit addressing. So far, XR2600 Series designs have been a tussle between speed, size and stability where everything lost. They have either: ⋅ Failed to allocate 48KB ... |
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Forum: Hardware Topic: 16*16 Pixel Tile Video Display And Video Codec |
| Sheep64 |
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Posted: Fri Apr 15, 2022 2:26 pm
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Replies: 11
Views: 3922
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| ... scaled out. Likewise, it is highly re-assuring to know that it could be fitted in a RAM or ROM socket; such as the ROM socket of POC2.0 or XR2602. It is most re-assuring to know that the Commander X16's VERA is available as an alternative display system. |
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Forum: Hardware Topic: Project Snail: 65C02 Crawling At 62.5kHz |
| Sheep64 |
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Posted: Tue Mar 22, 2022 12:58 pm
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Replies: 13
Views: 4427
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| ... than 4 inch. There is a noticeable difference in complexity with the parallel buses on one side of 6522 and the serial buses on the other side. On XR2602, all 10 vias are around the edge of the parallel buses. There are zero vias in the proximity of the serial buses. Furthermore, it is really easy ... |
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Forum: General Discussions Topic: Chips: prices and availability in 2022 |
| Sheep64 |
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Posted: Tue Mar 22, 2022 12:17 pm
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Replies: 10
Views: 2664
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| ... affects latching. ⋅ In stock, maybe: Aries DIP ZIF sockets. Annoyingly, this is the majority of significant components required to make XR2602 with 20 bit address-space, privilege bit and SPI/SNES interface. The simplified XR2601 requires 28C256, 74HC139 and 74HC595 but is otherwise ... |
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Forum: Hardware Topic: Project Snail: 65C02 Crawling At 62.5kHz |
| Sheep64 |
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Posted: Sun Mar 06, 2022 4:41 pm
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Replies: 13
Views: 4427
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| ... latency using one 74HC157, one 74HC138 and one 74HC139. Diagrams enclosed. For boot-strap, I recommended a simplified, one chip version to gmc . XR2602 only latches four bits of address: A16-A19. I was overly concerned by this limitation. It is possible for firmware to detect 20 bit/24 bit address-space. ... |
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Forum: General Discussions Topic: Chips: prices and availability in 2022 |
| Sheep64 |
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Posted: Tue Feb 22, 2022 7:50 pm
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Replies: 10
Views: 2664
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| ... "any news is good news" strategy. Avoid incompetence and you'll avoid delay. All of this is annoying because I hoped to make the first XR2600 board with reliable components but I may have to substitute junk components. Either way, I will be keeping my options open by writing NMOS compatible ... |
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Forum: Hardware Topic: Project Snail: 65C02 Crawling At 62.5kHz |
| Sheep64 |
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Posted: Tue Feb 22, 2022 7:22 pm
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Replies: 13
Views: 4427
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| ... facing inwards so that the rim would be ground and the inner part of the board would have a short, fat power rail. Actually, a draft version of XR2602 has a snail-like spiral for power. This is very pleasing but quite impractical. With 0.1 inch grid, I was working on points basis where 20 pins ... |
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Forum: Hardware Topic: Project Snail: 65C02 Crawling At 62.5kHz |
| Sheep64 |
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Posted: Wed Feb 02, 2022 4:54 pm
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Replies: 13
Views: 4427
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| ... and WAN. However, I've already got the anachronism of PS/2 keyboard and mouse. I'm not adding octal mainframe channel numbers. The simplified XR2601 omits clock stretching, address latching and a second tier of (optionally chip stacked) 74HC138 address decode. Jumpers select one 4*8KB bank ... |
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Forum: Hardware Topic: Design challenge: 6502-based EPROM programmer |
| Sheep64 |
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Posted: Wed Feb 02, 2022 4:13 pm
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Replies: 145
Views: 16318
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| ... with a power, clock and serial data bus which ran around the edge. I was more disappointed by component orientation. In an draft version of the XR2601 main board, I found that inward DIP components allowed ground around the outside and an inner power rail. However, this is only useful is very ... |
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Forum: General Discussions Topic: Extra large keyboard |
| Sheep64 |
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Posted: Sun Jan 09, 2022 8:25 pm
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Replies: 4
Views: 1848
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| ... a payment mechanism, all boards of 100mm*100mm or less will be USD5 plus a global flat rate of USD5 for shipping. This includes the forthcoming XR2600 Series main boards. Newbies may be particularly interested in the growing list of giveaway parts which include my 5V, reversible indicator lights |
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