diff --git a/BlueSCSI/firmware.uf2 b/BlueSCSI/firmware.uf2 new file mode 100644 index 0000000..570378b Binary files /dev/null and b/BlueSCSI/firmware.uf2 differ diff --git a/README.md b/README.md new file mode 100644 index 0000000..362505f --- /dev/null +++ b/README.md @@ -0,0 +1,91 @@ +VAXstation 2000 SCSI Patched ROMs +================================= + +The VAXstation 2000 is a fantastic little "shoe box" VAX computer. A little +slow maybe but a great entry to the wider world of DEC's VAX computers. +However it is somewhat lacking in one area: storage. It has one (optional) +internal hard drive (mine came with a 150MB RD54) and one (optional) +external hard drive - both of the MFM variety. That's not a big amount of +storage, and old MFM drives are as you probably know prone to stiction and +bad blocks, if they even work at all. + +The VAXstation 200 does have a SCSI interface, however it was only intended +to be used with the optional external TZK50 tape drive, and as such has never +had any real support for adding hard drives, and it certainly cannot boot +from a SCSI hard drive even if the operating system supported accessing one. + +But all is not lost. An experimental patch set for the VAXstation 200 was +created (but never officially released) to add full SCSI support to both the +internal ROMs and to VAX/VMS, but only one specific version. Which is what +we have here. + +Using the patches is not the easiest thing in the world, since you need +an already working installation of VAX/VMS 5.5-2 (yes, that exact version) +in order to run the patches. And if you don't have a working hard drive +to operate the VAXstation on, how are you going to get a working installation? +The answer is to net-boot it with a VAX cluster. But doing so makes it +rather hard to then make a standalone image. But it can be done with a bit +of shoehorning. Which thankfully we have done for you. In the releases +section you will find a set of BlueSCSI hard drive images that should allow you +to boot a VMS installation (dka200) that is ready to be completed with +your own details, along with the installation source files (dka300) which +the installation will ask you for. + +Using it +-------- + +In short: + +1. You need to upgrade your ROMs using the four ROM images (b1-b4) in the ROMs + directory. You will need four new 64kB EPROMs to burn the images to then + replace the ROMs on your VAXstation 2000's motherboard. + +2. Connect the BlueSCSI to the SCSI bus (important: see belo), making sure to enable termination if + you don't have the TZK50 tape drive attached or an external terminator. + +3. Boot from the dka2 device: + +``` +>>> boot dka2 +``` + +4. Complete the installation following the on-screen prompts. When it asks for + the installation media tell it `dka300`. + +5. Install the patched binaries into the installed os: + +``` +$ mount/over=id dka300 +%MOUNT-I-MOUNTED, VMS552 mounted on _DKA300: +$ set def dka300:[scsi.bin] +$ @install +``` + +Now the long version: + +Installing the ROMs is pretty straight forward. There's 4 EPROM chips on the motherboard +which need replacing. + +{image here} + +Note the order, as marked on these ROMs. + +The BlueSCSI (which should be a BlueSCSI II Desktop version so you get the proper 50 pin +IDC connector) will not work with the VAXstation out of the box due to the VAXstation +being from the dawn of SCSI and not working in quite the same way as other systems +(the joys of old computers...) so the BlueSCSI will need to be modified in order to work. + +The problem here is that the SEL pin and RST pin of the SCSI are weakly tied together inside the +BlueSCSI, so when the RST pin is asserted by the SCSI initiator the SEL pin gets pulled +low, which shouldn't happen. Most things don't care - but the VAXstation does, and when that +happens it just gives up trying to do anything on the SCSI bus ever again. So we need +to separate those two signals. This needs some careful SMD rework. + +1. Remove the resistor R61. This is the resistor that ties the two signals together. +2. Connect the left hand pad of R61 to the pin GPIO17 of the Raspberry Pi Pico. This + gives the MCU direct control over the SEL pin. +3. Install modified firmware into the Pi Pico which moves the SEL functionality to + GPIO 17. + +This modification uses one of the pins that was used for I2C for the SEL pin, so you will +no longer be able to use the I2C connector on the BlueSCSI.