View Profile: Eudimorphodon - Vintage Computer Forum

Today, 01:07 PM

Eudimorphodon replied to a poll System architecture for a Z380 TRS-80 compatible. in Tandy/Radio Shack

I was referring to this: And like I said, from reading the creator's description at least, this card basically run the whole show; there's a...

55 replies | 868 view(s)

Yesterday, 07:03 PM

Eudimorphodon replied to a thread Why did RS place a power key switch on external HDs? in Tandy/Radio Shack

Little known trivia: Radio Shack was reluctant to release a hard drive for the Model I because the only prototype they could cook up needed to be...

5 replies | 155 view(s)

Yesterday, 03:08 PM

Eudimorphodon replied to a poll System architecture for a Z380 TRS-80 compatible. in Tandy/Radio Shack

If you want a laugh here's my lo-tech approach. The big black chip in the lower left is an AVR324 that's programmed to do address generation and...

55 replies | 868 view(s)

Yesterday, 02:29 PM

Eudimorphodon replied to a poll System architecture for a Z380 TRS-80 compatible. in Tandy/Radio Shack

The linked RC2014 card above uses a Raspberry Pi Zero, and essentially all it does is DMA. (It uses some external hardware glue to regularly pause...

55 replies | 868 view(s)

Yesterday, 12:45 PM

Eudimorphodon replied to a thread A dumb (but obscure) Commodore PET video implementation question: Hardware cursor? in Commodore

... The IEEE topic opens up a whole can of worms, actually. If this actually comes together I'm going to want some kind of storage device, but I'm...

23 replies | 849 view(s)

Yesterday, 12:41 PM

Eudimorphodon replied to a thread A dumb (but obscure) Commodore PET video implementation question: Hardware cursor? in Commodore

I'm *pretty sure* cursor blink is done by counting the vertical refresh IRQs. There's a mention of it in here, and I think I may have seen the code...

23 replies | 849 view(s)

Yesterday, 12:25 PM

Eudimorphodon replied to a poll System architecture for a Z380 TRS-80 compatible. in Tandy/Radio Shack

Just googled up RC2014, and looking at the structure of the bus... When you say "z380 with simple hardware compatibility", do you mean a single card...

55 replies | 868 view(s)

Yesterday, 10:51 AM

Eudimorphodon replied to a thread 4Mb vga resolution in Vintage Computer Hardware

The thing to watch out for is many cards newer than the mid-1990's don't actually support "packed" 24-bit color (IE, three bytes per pixel), they...

7 replies | 107 view(s)

Yesterday, 10:35 AM

Eudimorphodon replied to a poll System architecture for a Z380 TRS-80 compatible. in Tandy/Radio Shack

That's pretty much what I was talking about on the nose; Realtek is still churning out "full" 8019s and they also sell a similar chip which has the...

55 replies | 868 view(s)

Yesterday, 10:28 AM

Eudimorphodon replied to a poll System architecture for a Z380 TRS-80 compatible. in Tandy/Radio Shack

Incredibly stupid idea: if you're confident/eager to get TRS/LS-DOS 6+ running on an eZ80 and the switch to the z380 is entirely forced on you...

55 replies | 868 view(s)

January 20th, 2021, 05:36 PM

Eudimorphodon replied to a poll System architecture for a Z380 TRS-80 compatible. in Tandy/Radio Shack

Another fact of life that's pretty much slam-dunk argument for doing some kind of processor offload is if the goal is to let your Z80/6502/whatever...

55 replies | 868 view(s)

January 20th, 2021, 04:25 PM

Eudimorphodon replied to a poll System architecture for a Z380 TRS-80 compatible. in Tandy/Radio Shack

To be clear, I'm pretty much agnostic about most cases of using microcontrollers as elements for replacing obsolete/unobtanium hardware parts for...

55 replies | 868 view(s)

January 20th, 2021, 03:35 PM

Eudimorphodon replied to a thread A dumb (but obscure) Commodore PET video implementation question: Hardware cursor? in Commodore

Resurrecting this thread with another ignorant question about arcane Commodore/6502-family obscurities. This is specifically about how the VIA is...

23 replies | 849 view(s)

January 20th, 2021, 01:39 PM

Eudimorphodon replied to a poll System architecture for a Z380 TRS-80 compatible. in Tandy/Radio Shack

Some of the other constraints that EtherNUT code has to deal with is running on microcontrollers with as little as 4K of RAM (It's an IoT OS, after...

55 replies | 868 view(s)

January 20th, 2021, 12:36 PM

Eudimorphodon replied to a poll System architecture for a Z380 TRS-80 compatible. in Tandy/Radio Shack

I have to admit I'm not sure where realistically this would ever be a worry for a machine like this, especially if it's primarily in a client role...

55 replies | 868 view(s)

January 20th, 2021, 11:38 AM

Eudimorphodon replied to a poll System architecture for a Z380 TRS-80 compatible. in Tandy/Radio Shack

Hey, I don't mind hearing about CPLDs. ;) I'm still mucking around with GALs so they're a bit out of my league yet, but maybe one of these days... ...

55 replies | 868 view(s)

January 19th, 2021, 09:07 AM

Eudimorphodon replied to a thread Force a 1.4MB 3.5" to only act as a 720K drive? (CoCo) in Vintage Computer Hardware

Whoever told you that is misinformed. On a “standard” 1.44mb drive the density selection jumper directly controls the write current, if you insert a...

4 replies | 120 view(s)

January 17th, 2021, 04:48 PM

Eudimorphodon replied to a thread IBM 5160 ? about XT-IDE in PCs and Clones

On the flip side, I sort of wish the XUB configuration software would incorporate direct support for SST flash chips one of these days. The 128KB...

11 replies | 425 view(s)

January 15th, 2021, 07:42 PM

Eudimorphodon replied to a thread Composite color artifacts: made by design or happy coincidence? in PCs and Clones

The details give me a headache, but the long and short of it is the circuitry that has to trap out the narrow bandwidth chroma pulses and compare...

19 replies | 346 view(s)

January 15th, 2021, 07:22 PM

Eudimorphodon replied to a thread Composite color artifacts: made by design or happy coincidence? in PCs and Clones

But the chroma data isn’t shoved into the back porch, only the color burst lives there. (Which is the sync/phase reference for the chroma data...

19 replies | 346 view(s)

January 15th, 2021, 04:08 PM

Eudimorphodon replied to a thread Composite color artifacts: made by design or happy coincidence? in PCs and Clones

It's *possible* in CGA's case that IBM never actually thought of it and the fact that the hardware is capable of it is a happy accident resulting...

19 replies | 346 view(s)

January 15th, 2021, 11:22 AM

Eudimorphodon replied to a thread Adding a CF card slot to a 5170 without wasting an expansion card bay? in PCs and Clones

A stock 5170's going to have an MFM + FDC board in it, not IDE, of course. But if you put a generic IDE/FDC card in there and want to just play the...

27 replies | 694 view(s)

January 14th, 2021, 03:09 PM

Eudimorphodon replied to a thread Adding a CF card slot to a 5170 without wasting an expansion card bay? in PCs and Clones

Just tossing this out there: they make IDE-to-SD and even IDE-to-Micro-SD boards that you could cable up instead of a CF adapter if you want...

27 replies | 694 view(s)

January 13th, 2021, 06:30 PM

Eudimorphodon replied to a poll System architecture for a Z380 TRS-80 compatible. in Tandy/Radio Shack

What are you planning to use for the video output hardware? And keyboard input, so far as that goes. (Interface to an actual matrix, or some kind of...

55 replies | 868 view(s)

January 13th, 2021, 05:50 PM

Eudimorphodon replied to a thread 2021 Vintage plans, and 2020 lessons learned. in General Vintage Computer Discussions

So, my list for 2021 shakes out something like this: Build a complete "working" computer based on the video dingus I've been futzing around with...

1 replies | 110 view(s)

January 12th, 2021, 05:46 PM

Eudimorphodon replied to a thread Dr. Suding questions in General Vintage Computer Discussions

... so, in other words they successfully copied the *behavior* of the “canonical” 8080 accurately with the Z80. That says nothing about the hardware.

21 replies | 510 view(s)

January 12th, 2021, 01:58 PM

Eudimorphodon replied to a thread Dr. Suding questions in General Vintage Computer Discussions

Electrically the 8080 and the Z80 aren't very much alike at all. The 8080 has an 8-bit ALU <strike>and a multiplexed address bus</strike>(*), the...

21 replies | 510 view(s)

January 12th, 2021, 10:24 AM

Eudimorphodon replied to a thread Dr. Suding questions in General Vintage Computer Discussions

Grrr. That one rankles me every time I see it. I understand he's a nice enough guy and means well, but he should know better. Re: the "slow scan...

21 replies | 510 view(s)

January 11th, 2021, 03:52 PM

Eudimorphodon replied to a thread Do VGA monitors distinguish between NTCS and PAL? in PCs and Clones

Here's a mind-numbing cross reference of Commodore 1080/1084 family monitors. The vast majority of the individual SKUs supported both analog and CGA...

12 replies | 409 view(s)

January 11th, 2021, 10:57 AM

Eudimorphodon replied to a thread Has a game ever used the IBM 5151's "long" P39 phosphor to get around charset limits? in PCs and Clones

My TRS-80 Model I came with one of those fabric glare filters stuck to it. I did inexplicably like it a lot; obviously it doesn't actually help with...

21 replies | 748 view(s)

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