pbirkel@gmail.com
Veteran Member
I wasn't sure where to place this topic, but as the broader context is a CNC mill controller using a Data General Nova-family controller <Minis and Mainframes> seemed as appropriate as any other forum.
I'm working to reverse-engineer a BostoMatic CNC controller from the early-mid 80's that uses a Fairchild F9445 VLSI implementation of the DG Nova 3 ISP. Documentation is non-existent, including even marketing literature, so it's slow going and early days. I believe that earlier controllers from the same OEM likely used actual DG Nova 3 processors, so my general approach is to treat a normal Nova 3 as my technology-baseline and then work to understand the differences in this OEM custom implementation. For starters it's pretty clear that the OEM wasn't interested in a DG-compliant backplane. There's some pretty (IMO) novel stuff going on with the backplane signals, although perhaps no more unusual than some of the pre-Nova 3 implementations.
It appears that the base installation boot-loaded from a paper tape (which appears to have been a serial-interface device, not parallel), but could be upgraded to instead boot-load from a 3.5" FDD if a controller was installed; that controller is based on a Western Digital FD1791. It appears that a single boot-loader serviced both devices, which determined by front panel switch positions. FWIW there was a further upgrade possible to a Winchester HD that appears to have has a real file system (of some sort; format unknown).
Because of the simple transition from paper tape to floppy disk I infer that the boot-loader simply treated the FDD as a series of sectors, incrementing from track 0 until encountering an end-of-file indication of some form, perhaps a null-containing sector. I also believe that both the tape and the FDD had the possibility of continuing to load additional content "from the same stream" under operator control (in effect a simple "continue" switch).
It appears that the floppy disk could be written on a standard PC, but IMO it's extremely unlikely that anything like FAT16 was supported. Instead the PC FDD controller would have been called upon to write a sector-by-sector binary byte-stream that the CNC controller could then serially read. AFAIK there's nothing preventing a standard PC FDD controller being used in this manner by a specialized application.
I'm completely unfamiliar with this sort of primitive use of a FDD as a byte-stream device, but I assume that it wasn't a completely novel usage.
Has anyone seen (or heard) of this sort of use? If so then where, when, how ...
Thank you for your thoughts!
I'm working to reverse-engineer a BostoMatic CNC controller from the early-mid 80's that uses a Fairchild F9445 VLSI implementation of the DG Nova 3 ISP. Documentation is non-existent, including even marketing literature, so it's slow going and early days. I believe that earlier controllers from the same OEM likely used actual DG Nova 3 processors, so my general approach is to treat a normal Nova 3 as my technology-baseline and then work to understand the differences in this OEM custom implementation. For starters it's pretty clear that the OEM wasn't interested in a DG-compliant backplane. There's some pretty (IMO) novel stuff going on with the backplane signals, although perhaps no more unusual than some of the pre-Nova 3 implementations.
It appears that the base installation boot-loaded from a paper tape (which appears to have been a serial-interface device, not parallel), but could be upgraded to instead boot-load from a 3.5" FDD if a controller was installed; that controller is based on a Western Digital FD1791. It appears that a single boot-loader serviced both devices, which determined by front panel switch positions. FWIW there was a further upgrade possible to a Winchester HD that appears to have has a real file system (of some sort; format unknown).
Because of the simple transition from paper tape to floppy disk I infer that the boot-loader simply treated the FDD as a series of sectors, incrementing from track 0 until encountering an end-of-file indication of some form, perhaps a null-containing sector. I also believe that both the tape and the FDD had the possibility of continuing to load additional content "from the same stream" under operator control (in effect a simple "continue" switch).
It appears that the floppy disk could be written on a standard PC, but IMO it's extremely unlikely that anything like FAT16 was supported. Instead the PC FDD controller would have been called upon to write a sector-by-sector binary byte-stream that the CNC controller could then serially read. AFAIK there's nothing preventing a standard PC FDD controller being used in this manner by a specialized application.
I'm completely unfamiliar with this sort of primitive use of a FDD as a byte-stream device, but I assume that it wasn't a completely novel usage.
Has anyone seen (or heard) of this sort of use? If so then where, when, how ...
Thank you for your thoughts!