Altair - RC2014 Hybrid
Posted: April 22nd, 2021, 10:00 amI love the look and function of the Altair clone concept. For me, the only thing missing was the ability to build and experiment with hardware - simple cards on a backplane (which was what got me into the hobby that turned into a career in 1981). The RC2014 ecosystem seemed more hobbyist friendly than recreating the S100. Foth this use case, I decided to experiment to see if the best of the Altair Clone and RC2014 could be combined.... a modern hobbyist Z80 varant Altair. These are my own motivations.
Mike has been *extremely* helpful. The case and interface cards are beautiful.
To these I have added
1. Custom Front Panel Interface card - that replicates most of the functionality of Mike's and interfaces to the RC2014 backplane. I am having fun decoding the M1 EI and DI op-codes + IAK cycles to accurately support the the INTE state. As for the stack operations ....
2. Z80 CPU card that has logic to separate the CPU bus from the backplane and support the wait-state injection of instructions and data to support the Examine and Deposit operations.
CPU card also has a simple DMA and reset manager that allows separate reset control of the CPU and Bus. DMA allows me to inject code and data into memory. The reset management allows for memory and IO initialization of the bus while the CPU is in reset.
Successes so far: No smoke, Switches and LEDs support control of Reset, Run/Stop/SingleStep, Examine(N) and Deposit(N). DMA works both during operation and 'managed reset'. At present I am booting to a ROM monitor.
ToDo: Operationalize the DMA to allow 'all RAM' operation with selected front panel configuration settings (e.g. copy boot software to RAM) and emulate Mike's startup configurations.
Then: Implement Altair hardware (ACIA, FDD etc. with adjustable compatibility mappings) on the RC2014 bus.
I am loving using the panel for debugging and patching!!!!
A big thank you to Mike and the group for all of the inspiration.
Steve
Mike has been *extremely* helpful. The case and interface cards are beautiful.
To these I have added
1. Custom Front Panel Interface card - that replicates most of the functionality of Mike's and interfaces to the RC2014 backplane. I am having fun decoding the M1 EI and DI op-codes + IAK cycles to accurately support the the INTE state. As for the stack operations ....
2. Z80 CPU card that has logic to separate the CPU bus from the backplane and support the wait-state injection of instructions and data to support the Examine and Deposit operations.
CPU card also has a simple DMA and reset manager that allows separate reset control of the CPU and Bus. DMA allows me to inject code and data into memory. The reset management allows for memory and IO initialization of the bus while the CPU is in reset.
Successes so far: No smoke, Switches and LEDs support control of Reset, Run/Stop/SingleStep, Examine(N) and Deposit(N). DMA works both during operation and 'managed reset'. At present I am booting to a ROM monitor.
ToDo: Operationalize the DMA to allow 'all RAM' operation with selected front panel configuration settings (e.g. copy boot software to RAM) and emulate Mike's startup configurations.
Then: Implement Altair hardware (ACIA, FDD etc. with adjustable compatibility mappings) on the RC2014 bus.
I am loving using the panel for debugging and patching!!!!
A big thank you to Mike and the group for all of the inspiration.
Steve