RESTORED 1130 POWER RAIL LEVEL LEADING TO NEW SYMPTOMS When working on the disk drive attempting to make the adjustments for seek behavior, I checked the voltage at a pin that the Field Engineeering Maintenance Manual (FEMM) suggested be tested. The expected level was 8V but I found it at 6.2V. I verified the incoming power rails - +3V, -3V and +6V - only to find that the last was only at 5V. I…
ASSEMBLED NEW VERSION OF 2310 INTERFACE BOARD The Virtual 2315 Cartridge Facility (V2315CF) has a component that is a board that interconnects the cables from the IBM 1130 disk controller logic, the internal disk drive, and the main V2315CF unit, as well as a few other functions. I adjusted the design to include electronic switches that connected the signals between the internal disk and the disk…
TRYING OUT A TERMINATOR AT THE 1130 BACKPLANE TO IMPROVE SIGNAL The +Access Ready signal that is generated by the disk drive in real mode of the Virtual 2315 Cartridge Facility (V2315CF) or by the V2315CF in virtual mode. It is feedback to the disk controller logic in the 1130 as it moves the disk arm to seek to different cylinder locations. There was some ringing and glitches on the signal which…
STILL FOCUSING ON SIGNAL INTEGRITY FOR V2315CF SEEK I was not happen with the glitching and malformed signals going into the 1130 for the +Access Ready feedback signal. I am determined to clean this up and not just hope that the Virtual 2315 Cartridge System (V2315CF) works in spite of the signal distortion. The first thing I did was to remove the terminator resistors for that signal, to see what…
NEW TERMINATOR BOARD IMPROVES BUT DOES NOT FIX V2315CF SEEK TRACKING The Virtual 2315 Cartridge Facility (V2315CF) watches the control signals between the 1130's internal disk controller and the internal disk drive (named 2310 or 13SD or RAMKIT). It shadows the position of the disk arm as commanded by programs issuing XIO Seek commands, since the data to be returned when the software reads from…
ADJUSTING THE FORWARD CRASH STOP ON THE INTERNAL DISK DRIVE Crash stop when arm is not at 202 Arm against crash stop just past 202 In order to be safe, I changed the stop to a gap of .008", giving the maximum margin for acceleration while still blocking the ability of the arm to move to cylinder 203. With an attempt to move 20 mil, the arm should stop and the detent should still fall back into the…
FINISHED MODIFYING TERMINATOR BOARD WITH NEW RESISTOR VALUES The terminator board that fits into the Virtual 2315 Cartridge Facility (V2315CF) main unit is the same one used successfully with the unit in its original role as George Wiley's RK-05 Emulator connecting to a DEC computer to emulate a disk drive that is a derivative of the IBM drive. The terminator implemented the same resistance values…
TESTING NEW SHADOWING MECHANISM I loaded the FPGA and PICO of the Virtual 2315 Cartridge Facility (V2315CF) with the updated functionality and repeated the tests from before - using the disk in real mode, issuing seeks of various distances. I wanted to check that the V2315CF reported the ending cylinder number that is expected from the distance of the seek, that the disk arm moved to the correct…
SITUATION BEING ADDRESSED When we have loaded a valid mini cartridge into the Virtual 2315 Cartridge Facility (V2315CF) it should remain active regardless of whether we power the disk drive down and back up. In the real world, a 2315 cartridge that had been inserted in the drive will still be there when the switch if flipped to run. So too, the virtual cartridge should remain available if we spin…
NEW APPROACH FOR SHADOWING SEEK IN REAL MODE I made changes to the logic for the FPGA in the Virtual 2315 Cartridge Facility (V2315CF) to handle the glitches I saw on +Access Ready as it was passed to the 1130 disk controller logic. That feedback signal generated by the disk drive had glitches which looked like spurious changes of state to the disk controller, resulting in failure to drive the…
BETTER LOGIC ANALYZER RECORDINGS AND THEIR RESULTS I recorded several seek movements - 1, 2, 3 and 193 cylinder movements. What I observed in all of these are glitches or spurious changes of +Access Ready which caused the 1130 disk controller to malfunction. For example, here I zoomed in on +Access Ready , the second signal in the trace, dropping low for a short (invalid) period which triggers the…
UPDATES MADE TO LOGIC OF THE V2315CF I made a few updates to the C code for the PICO and the Verilog for the FPGA of the Virtual 2315 Cartridge Facility (V2315CF) based on the prior day's testing. I had noticed that a completely valid sequence of steps did not perform in a way that makes sense. The state machine was changed to handle this in a more reasonable way. The user inserts a mini cartridge…
IMPEDANCE FOR SIGNALS IS COMPLICATED IBM engineers the 1130 for 92 ohm impedance on cables, although in practice there are ribbon cables, traces on printed circuits, wire wrap on the backplane, and twisted pair wiring involved in the path between the 1130 and its internal disk drive. However, since the engineering goal was matching 92 ohm impedance, I will use that as a working start. The 2310…
LOGICALLY THE V2315CF SITS BETWEEN THE DISK AND THE 1130 COMPUTER The cable that ran from the disk controller logic cards in gate A compartment C1 of the 1130 originally plugged into the internal 13SD disk drive, but we inserted the 2310 Interface Card between the two. The original cable plugs into that card and a new cable from the card plugs into the disk drive. Two ribbon cables connect the…
MORE OBSERVATIONS OF SIGNAL FOR A SEEK WITH AN ODD COUNT I used my hand programmed code to make several seeks of different lengths in order to watch what the disk drive itself as well as the V2315CF logic saw. For example, when I requested a seek of 161 tracks, it should have stopped the disk arm at 161 and reported 161 on the V2315CF log. What I saw instead was the arm stopped at 141 and the log…
HAND CODED SEEK PROGRAM EMPLOYED TO CHECK BEHAVIOR I had whipped up a short program that I toggled into core which would walk through a list of seek amounts and issue them to the drive. I stepped through it to see if the reported cylinder in the Virtual 2315 Cartridge Facility (V2315CF) log matched where it should stop. ANOMALIES DETECTED WHICH I HAVE TO INVESTIGATE FURTHER As an example of a…
CARTINTERFACE - TOOL TO MOUNT MINI 2315 CARTRIDGE ON PC VIA USB The Virtual 2315 Cartridge Facility (V2315CF) employs microSD cards to hold a disk volume with a file that is a virtual image of a 2315 disk cartridge. These cards are mounted on a small circular PCB that is the top of a mini cartridge, looking like a tiny version of the 2315 cartridge, with a 2x4 header that plugs into the V2315CF…
1627 CONTROLLER CARD SUBSTITUTE WAS ADOPTED AND IS IN USE Friends at a museum in Europe have made use of the 1627 github project to build a substitute card and install it per the instructions. They have already restored a 1627 Plotter but did not have the controller card installed in their 1130 to make use of it. Today they first tested it out - it is working perfectly and soon they will try out a…
PROGRAMMED THE INITIALIZATION MEMORY FOR THE FPGA Once I had the license in hand for IceCube2 I could synthesize and generate the bitstream for the FPGA device used in the Virtual 2315 Cartridge Facility (V2315CF) main unit. I grabbed the Lattice HA-USBN-2A programming cable and plugged it into the V2315CF, then powered up the V2315CF. fired up the Diamond application and used it to update the…
CLEAN INSTALL OF VS AND PICO SDK - AN EXERCISE IN PATIENCE I need a functional development environment for the Raspberry Pi PICO but after the debacle with AI misdiagnosing problems and directing changes to my prior install, I had to uninstall and start over. AI had me change the terminal type - command shell, power shell, etc - multiple times which impacts how each new suggestion works or doesn't…
RESUMING CLAUDE WORK Another few hours, still zip. I gave up when finally it did a screen scrape and found some report of issues with TinyUSB and the PICO board support. It then recommended giving up on the Arduino IDE approach and going over to the Visual Studio code that all the other AI systems found and regurgitated. DISCOVERY ON MY OWN - CODE OFFERED BY AI FLAWED IN KEY WAY I did my own…
HAVING HAD A POOR EXPERIENCE WITH GOOGLE GEMINI, I TRIED COPILOT I decided to give Microsoft's Copilot a try and posited the same requirement. Use a PICO to connect to a PC over USB as a disk drive showing the contents of a microSD card, accessed by SPI and formatted in FAT13. I chose the approaches that used Visual Studio and the PICO SDK. EIGHT HOURS OF HAND TO HAND BATTLE, NO SUCCESS WITH…
RESOLUTION OF THE ISSUE As I covered in my last blog post, the addition of a braided ground wire with many fine strands was sufficient to solve the high frequency impedance of the ground connection. The board is now solid as a rock. RERAN CPU DIAGNOSTIC AND MEMORY DIAGNOSTIC SUCCESSFULLY All diagnostics run clean, thus the memory and indeed the CPU are working properly. I can move back to testing…
VIRTUAL 2315 CARTRIDGES STORE THE IMAGE ON A MICROSD CARD INSIDE HOLDER The Virtual 2315 Cartridge Facility (V2315CF) makes use of microSD cards to hold a file with the contents of a 2315 Disk Cartridge for use in the disk drive of an IBM 1130 system. The microSD card is kept in a holder that appears to be a miniature 2315 cartridge, presenting pins on the edge that plug into the main box of the…
FOUND ONLINE COMMENTS THAT SUGGEST FORMATTING OF MAC IS AN ISSUE Some internet messages suggested that Lattice expects the MAC address of the network interface to be formatted a specific way, without hyphens or colons as most systems display them. My first request changed the subject line to Renewal from their boilerplate New iCEcube2 License Request wording. I then changed it to what they had,…