6502.org

Oscillator can drive W65C02 directly up to about 30Mhz. At higher frequency than 30 Mhz, I found it necessary to drive it with CPLD, but not necessarily through a divided-by-2 flip flop. I don’t think it is the clock symmetry, rather the faster slew rate of the CPLD output.
Bill

Rev1 of 65ALL has fixed all known problems. It bootstraps from CF to monitor; VGA display and PS2 keyboard are working. It is a standalone computer but I can load updates and applications from workstation via serial port. It can load and run BadApple, Game of Life, and passed Dormann's instruction tests. I'm putting it aside now because I have several new pc boards to check out. My plan is to port DOS/65 to it and work toward a self-hosting computer. Current discussion about editor and high-level program running on 6502 are very applicable to 65ALL. DOS/65 has CP/M equivalent ED and BASIC, but I hope to port Miguel Garcia's TE screen editor. For high level language Forth seems the most compact language for 8-bit processors, but sadly I have no working Forth experience. On the other hand, I've programmed mostly in assembly and have forgotten most of my C/C++, so I might as well start afresh with Forth.
Bill

Hi Bill,

That's a nice standalone system... kudos on it!

I've been working on a minor update to DOS/65 Version 3.20, going to 3.21. It cleans up a few things between CCM and PEM and a slight change to SIM. Overall size is the same, but CCM is a bit larger, PEM is a bit smaller (both are now contained in 2.5KB) and SIM is still contained within 1KB. I also changed the default disk parameters to 4KB block sizes, so the allocation tables are half the size at 256 bytes each. With 8- 8MB drives, total size is 6KB for CCM/PEM/SIM and 2KB for allocation maps.

I have feedback from users that EPM7128SQC100 (100-pin QFP) is expensive, difficult to acquired, hard to solder and has higher percentage of locked JTAG which render it useless. (I must've gotten lucky with my existing stockpile of used EPM7128SQC100.) Any rate, EPM7128S in PLCC84 package is much easier to get and easy to test and replace if defective, so I've redesigned 65ALL with PLCC84 version. Software is compatible with 100-pin QFP version EXCEPT I2C interface is eliminated due to insufficient IO pins. I had a choice of either 115200N82 serial port or I2C and I picked serial port which is useful for files transfer. 65ALL has 3 expansion slots so either I2C or serial port can be added via expansion IO board, but serial port is more useful especially during the software development phase, so I picked the serial port function.

The design is currently being fabricated at JLCPCB. It is 4-layer, 100mmX100mm
Bill

Hi Bill
Looking forward to see how this works out. I have a few EPM7128 in PLCC84 left from the TrainerCPLD so I can try this out.
Larry

I've created a repository for 65ALL rev2 design information. https://www.retrobrewcomputers.org/doku ... 5allr2home

The pc board is not proven right now so I don't recommend downloading and sending the gerber photoplots to board fab house.
Bill

I assembled the PLCC84 version of 65ALL this morning. It is working.
Bill

That's great Bill I'll give it a go. Even soldering the RAM might be a challenge but my SMD technique is improving even using a fine point iron.

Something I should've known when designing for retro computers is retro frequently means used parts which are likely salvaged from old boards of uncertain conditions. So parts should be easy to remove, easy to test and replace. Used SMT parts are more likely to be damaged during removal and hard to test and replace, so I should stick with PLCC where possible. However, like you've said, PLCC84 is huge, but a component can be placed in the back, if that's any consolation.

I plan to port DOS/65 and port an text editor so I can use it to learn Forth.
Bill