Commenting to boost engagement - it is so sad that more people don't seem to be following along. I would figure that the same folks who enjoyed Ben Eater's 6502 computer would adore this as well like I do.
Thanks for the feedback. I would have to admit that so far I have not done anything to promote the channel. Its more of a video diary of how I build the project, which I have used on several occasions when I have forgotten what I did previously! I even impressed myself on one occasion! I will perhaps look to re-build the breadboard PC when I get Windows 1/2/3 running. I'll then perhaps put more effort into promotion! Feel free to mention on Hacker news or similar 😉 Thx Dave
Thanks, the CGA should be OK. I suspect getting the memory Map right for MCGA high res 640x480 2 colour and 320x200 256 colour will be tricky with a 6845 CRTC. In the 6809 version I didn't have to worry about PC compatibility so used 8 row address lines to get the 480 horizontal lines. MCGA used contiguous addresses for the pixels due to use of dedicated LSI chips. Still thinking about that one but will probably use a EEPROM to do the CPU memory map decoding. Dave
Believe it or not I picked up a fully working colour CGA monitor with the case in excellent condition, from a local computer retro faire for only £50 😮 . Thankfully although at some point in the 90’s I got rid of lots of now collectible ISA and other cards, I did keep one CGA card. I was using the card and monitor today in a genuine IBM PC motherboard (5 slots) also bought at the same computer faire (different date).
Ah well done with those purchases. I only started my own PC collection with a 486 DX in around 1992 and unfortunately I cleared out all of the old ISA & PCI cards etc more than a decade ago :-(
So thanks to IBM implementing a clock frequency helpful for standard US TV video generation, they threw away 5% of CPU frequency. All those PCs back in the 80’s could be safely over clocked by using a 15MHz crystal?
Agreed, and in fact to get the floppy disk controller working with programmed I/O (not DMA) I had to overclock the 8088 I have from 1983 to 16Mhz for it to be able to keep up with 1.44MB High Density Floppy drive data rate (500Kbps). PC Jr and Tandy 1000 only needed to use programmed I/O for standard density floppy drives so based frequency was OK (250Kbps). Dave
Commenting to boost engagement - it is so sad that more people don't seem to be following along. I would figure that the same folks who enjoyed Ben Eater's 6502 computer would adore this as well like I do.
Thanks for the feedback. I would have to admit that so far I have not done anything to promote the channel. Its more of a video diary of how I build the project, which I have used on several occasions when I have forgotten what I did previously! I even impressed myself on one occasion! I will perhaps look to re-build the breadboard PC when I get Windows 1/2/3 running. I'll then perhaps put more effort into promotion! Feel free to mention on Hacker news or similar 😉 Thx Dave
My observation is that with every increase in complexity, fewer people watch the videos. I think that's a shame too...
I'll do a TH-cam short on it for all those with short attention spans!
Even if I'm sure that you can do it, as you have done it many times in the past, I wish you good luck!
Thanks, the CGA should be OK. I suspect getting the memory Map right for MCGA high res 640x480 2 colour and 320x200 256 colour will be tricky with a 6845 CRTC. In the 6809 version I didn't have to worry about PC compatibility so used 8 row address lines to get the 480 horizontal lines. MCGA used contiguous addresses for the pixels due to use of dedicated LSI chips. Still thinking about that one but will probably use a EEPROM to do the CPU memory map decoding. Dave
Believe it or not I picked up a fully working colour CGA monitor with the case in excellent condition, from a local computer retro faire for only £50 😮 . Thankfully although at some point in the 90’s I got rid of lots of now collectible ISA and other cards, I did keep one CGA card. I was using the card and monitor today in a genuine IBM PC motherboard (5 slots) also bought at the same computer faire (different date).
Ah well done with those purchases. I only started my own PC collection with a 486 DX in around 1992 and unfortunately I cleared out all of the old ISA & PCI cards etc more than a decade ago :-(
So thanks to IBM implementing a clock frequency helpful for standard US TV video generation, they threw away 5% of CPU frequency. All those PCs back in the 80’s could be safely over clocked by using a 15MHz crystal?
Agreed, and in fact to get the floppy disk controller working with programmed I/O (not DMA) I had to overclock the 8088 I have from 1983 to 16Mhz for it to be able to keep up with 1.44MB High Density Floppy drive data rate (500Kbps). PC Jr and Tandy 1000 only needed to use programmed I/O for standard density floppy drives so based frequency was OK (250Kbps). Dave