Posts by bread80@mstdn.social
(DIR) Post #AZ3jf6HKPN70GhNoiO by bread80@mstdn.social
2023-08-24T11:04:04Z
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This is what the video output looks like. As far as I’m aware that’s not one of the ‘standard’ Amstrad bad RAM failure modes.
(DIR) Post #AZ3jf7BL37un4PaY1A by bread80@mstdn.social
2023-08-24T12:25:04Z
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Installed an LCD module so I can run so tests on the RAM.Works once I worked out to a) disable interrupts and b) use a 16 bit IO address to keep the other devices quiet.Bonus points if you can tell me what the full quote should be. It’s definitely the kind of thing I’d expect an Amstrad to say.
(DIR) Post #AZ3jf84ziCQzr1czlg by bread80@mstdn.social
2023-08-24T13:07:06Z
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Initial RAM test running. It prints a C if the byte read matches the one written.The correct results are showing from the 48th test value. That smells of an address bus issue.The wrong test values show $ff is being read. Is that the default RAM value at switch on? Or would tue values be random? It’s not ROM. I’ve set the default value to $00 in the programmer to rule that one out.
(DIR) Post #AZ3jf918E2wGlKpQO0 by bread80@mstdn.social
2023-08-24T14:57:46Z
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Based off the previous test result my theory is that 16 memory addresses return $ff, the next sixteen return correct data.This test displays a ‘Q’ for 16 bytes of $ff and ‘q’ for 16 bytes of correct data.Test result agrees with my theory. Which firmly points to and issue when address line A4 is low. Not sure why a fail would give $ff though. Possibly something isn’t getting enabled. So maybe a solder bridge.
(DIR) Post #Aa8bhzWBTs72ioViqG by bread80@mstdn.social
2023-09-25T21:17:36Z
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I've not come across this project before. A modular Commodore 64. Link (in German): https://www.forum64.de/index.php?thread/108496-tube64/&pageNo=10
(DIR) Post #AkljSu4tjGeb9GSYDI by bread80@mstdn.social
2024-08-08T20:47:30Z
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Checking the back of the #RP2350 #Pico-2 datasheet: THE GPIOS ARE 5V TOLERANT !!!#HappyDance #FistPumpImage 1: Specs for 'FT' (fault tolerant) pins.Image 2: Pin type definitions.Image 3: Listing of GPIO pins (not all shown 'cos there's far too many).(PS The rating for the Analogue/Digital pins which can be routed to ADCs is unclear, but I'm expecting they have the same ratings).
(DIR) Post #AkljSv6hu1hALAJVfk by bread80@mstdn.social
2024-08-08T20:52:05Z
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Imagine what the retro community can achieve with 48 pins which are all 5 volt tolerant. This thing should be able to emulate pretty much anything in a 40-pin package. #GameChanger #RP2350 (But outputs are still a maximum of 3.3V, so may need level conversion for full compatibility).
(DIR) Post #AkljSzZDJysIAjgKf2 by bread80@mstdn.social
2024-08-08T20:55:07Z
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Also of note in the #RP2350 (#Pico-2): There's now a way to use interrupts to communicate between PIOs. This will help solve situations where you need SMs to talk to each other but you have too many to fit into a single PIO.
(DIR) Post #AklnxIraXfBwWTz9Oa by bread80@mstdn.social
2024-08-08T21:50:34Z
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@thelastpsion Another option would be to use 5V pull ups.
(DIR) Post #AkrViC1T3odEjk0kGe by bread80@mstdn.social
2024-08-11T15:54:24Z
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@thelastpsion Yes.
(DIR) Post #AkxqZfQXd87HJRH51c by bread80@mstdn.social
2024-08-14T17:16:25Z
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@thelastpsion I’ve long gone past the point of deciding it’s easier to buy a bigger drive that it is to work out what to chop.
(DIR) Post #AlL86TK9ohjlBkax60 by bread80@mstdn.social
2024-08-25T21:38:45Z
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The second of my articles documenting creating a replacement Amstrad CPC gate array using a Raspberry Pi RP2350 microcontroller. This time I use a PIO, a DMA and an array of data to drive the six signals with fixed timings.Lots of nerdy detail for anyone wants to learn what a Pico is capable of, or for those who want a better understanding of the DMAs.https://bread80.com/2024/08/25/pico-garry-2350-part-2-fsigs-fixed-signals/#PicoGarry #PicoGarry2350 #Amstrad #AmstradCPC #RP2350 #Pico #Pico2
(DIR) Post #AlL86UogGhkNohsqJM by bread80@mstdn.social
2024-08-25T21:54:34Z
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BTW here's the scope trace of the signals being generated by the RP2350 at this stage.
(DIR) Post #AlLry0qqOEfESMmvyq by bread80@mstdn.social
2024-08-26T07:24:42Z
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@vik You we’re on the dev team? That’s really cool. Hardware or software?
(DIR) Post #AlLsWsZZA5SwurKfD6 by bread80@mstdn.social
2024-08-26T07:31:24Z
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@vik Were you ever in ACU magazine? If so then yes, I remember.
(DIR) Post #AlLseHklwG9x2X6au0 by bread80@mstdn.social
2024-08-26T07:32:45Z
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@vik Is it true that each dev was assigned a different ‘pack’ in the firmware? If so which was yours?
(DIR) Post #AlMQ8jXeU2igOn5x2m by bread80@mstdn.social
2024-08-26T13:48:01Z
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@vik How much of the firmware and ROMs was specified by Amstrad and how much by the dev team doing what they thought was best? I’m always impressed at how the machine goes way above the minimums required for a games machine. Things like the interrupt system and firmware jumpblocks have the feel of a ‘grown up’ business computer.
(DIR) Post #AlQDVou8BqnQv37xHU by bread80@mstdn.social
2024-08-28T09:45:20Z
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@vik Yes, the documentation was excellent. I still have my original Soft168(?) firmware manual and I still use it regularly.
(DIR) Post #Are9RZQn6gUbLZouiu by bread80@mstdn.social
2025-03-02T14:02:52Z
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A nice end to Sunday morning with a quick Delphi utility to convert a ROM binary to C source code.#firestarter #amstradcpc
(DIR) Post #AsDcapG5KPWaFCAwAS by bread80@mstdn.social
2025-03-19T16:58:54Z
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I’m too sleep deprived to tackle the diodes today but I’ve soldered on the key switch sockets. The footprints allow either direct soldering of the key switches or socket mounting. Using sockets allows you to swap to different switches. It also saves a tonne of money when building prototypes 😂#amstradcpc #mechanicalkeyboard