This page is a collection of notes made while I was getting familiar with this emulator at the RK8E workshop session in late June 2025 in the U.S. and subsequently at home in July/August 2025 in Melbourne.
Getting the images for the MicroSD card
The V1 emulator uses “.rk05” files. The V2 emulator uses “.rke” files. My emulators are all V2.
The RKE file is placed in the root directory of the SD card. The emulator uses the first RKE file that it finds in the root directory.
Vince has a collection of RKE files available for download, together with build tools to make those images.
The files are found at https://svn.so-much-stuff.com/svn/trunk/pdp8/vintagetek/rk05/build/
The 3 key downloadable images are:
OS8.RKE: This is a bootable version of OS/8. It contains RKA0 and RKB0. It’s loaded with a bunch of programs (including chess). When booted in the emulator, the little LCD screen shows the title as “os8.new”. That file (os8.new) is also in Vince’s directory and apparently can be booted in SIMH.
TEKRK0.RKE: This has a bunch of weird files from a testing system from “Electo Scientific” and is used for testing the SpaceWar hardware.
Vince says the “demos” and “8tools” directories here are also relevant (they contain build tools for building the above images).
Booting the RK05 emulator
To boot the RK05 Emulator (once the SD card is installed), do the following through the front panel of the PDP-8:
- Move HALT switch down and up again (to halt the machine)
- Set the switch register to 0030 and press ADDR LOAD
- Set the switch register to 6743 and raise DEP
- Set the switch register to 5031 and raise DEP
- Set the switch register to 0030 and press ADDR LOAD
- Press and release CLEAR
- Press and release CONT
Running diagnostics at Kyle’s house
We were running diagnostics off an RX02 emulator connected to Kyle’s PDP-8M.
The emulator has apparently been tested by the developer with DHRKAE and DHRKCx, but not with DHRKBG.
During testing of DHRKBG at Kyle’s house:
- One front board passed the test on both the real RK05 and the emulator
- Another front board passed the test on the real RK05 but NOT on the emulator
When running DHRKAE (diskless controller test) it’s OK to have a drive connected. But the RUN/LOAD switch must be in the LOAD position, or the test will immediately fail. Kyle was running with the switches set to 0200. When the diagnostic starts it says “SR= 0000”. This test takes about 10 mins to run on a real RK05. At the end of the first run it will say “PASS 0001\r\nWAITING”. You can press CTRL-R to progress to a second pass of the test.
DHRKBG was run with the same switch settings (0200) and also reported that “SR= 0000”. It takes approximately 40 mins to run on a real RK05. The first 2.5 minutes (approximately) are just testing positioning. R/W tests then follows until about t=18.25 mins at which time rapid positioning tests seem to resume. No status messages are displayed for any phase (or to say that it has moved from one phase to another).
Running Diagnostics back home in Melbourne
I was first trying to use DHRKBG.DG. Not sure where I sourced this from. It doesn’t ask which disk(s) you want to test or what SR settings you want to use, and always crashes about 2 minutes into the test. I suspect the problem is that the virtual switch register needs to be setup before running it.
I then found DHRKBG.SV on diag-games-kermit and with this, I was for the first time successfully able to run the diagnostic on my RK05 emulator on my 8/e, and later on my 8/f.
There is a great selection of RK diagnostic materials on deramp.com, including this PDF of DHRKBG.
Here is a sample printout from DHRKBG on my 8/f on 23.08.2025:
.RUN RXA1 DHRKBG RK8E DRIVE CONTROL TEST TEST (Y=YES OR N=NO): DISK0?Y DISK1?N DISK2?N DISK3?N SR= 0000 DHRKBF PASS 0001 RK8E DRIVE CONTROL TEST PASS COMPLETE DHRKBF PASS 0002 RK8E DRIVE CONTROL TEST PASS COMPLETE
A rough timeline when running DHRKBG is as follow:
- 00:00 : Test starts, no activity lights yet
- 00:05 : ONCYL light starts flashing, no RD/WT lights yet
- 02:05 : No activity lights are active
- 02:20 : RD/WT lights start flashing
- 37:45 : “Test Pass Complete” message prints (and automatically starts pass #2)
The hardware configuration used for the above test was:
- PDP-8/F chassis
- M8330, M8310, M8300, M837, M849, M8320
- “Set B” RK8E boards
- RK8E connected to Keypad/LCD version of RX01/02 emulator
- Mal’s MI8E/32K RAM board
- M8650 for console communications at 9600,M,8,1
- Mal’s CPLD UART connected to RPi SerialDisk server
The emulated drives I was using are:
- RXA0: OS8V3Q.RX1 (as boot device, as it has drivers for SDA0, SDA1, RXA0, RXA1, RKA0, RKA1)
- RXA1: RX1.DSK (on which DHRKBG.SV is stored)
- SDA0: diagpack2.rk05
- SDA1: scratch-pack.rk05
- RKA0/RKB0: os8.new
The RK05 emulator (with the same above hardware configuration) also boots and properly responds to a DIR command. However “RUN SYS BUILD” hangs the 8/f with the RUN light still on and doesn’t respond to CTRL-C.
The “os8.new” RK05 emulator file
A few notes about the “os8.new” RKE file:
- It successfully boots on the RK05 emulator
- The “SYS” device is RKA0 and has 837 free blocks
- The “DSK” device is RKB0 and has 1960 free blocks
- “VER” returns the following: “OS/8 – KBM V3Q – CCL V1F”
- “DIR” and “RUN SYS BASIC” both work fine
- “RUN SYS BUILD” doesn’t work (the system hangs with the RUN light on, and can’t exit with CTRL-C)
- “RES” reports that the installed devices are: “SYS,DSK,RKA1,RKB1,RKA2,RKB2,RXA0,TTY,LPT,RKA0,RKB0,PTP,PTR,T4,TDA0”
- It can successfully “DIR” RXA0, SDA0 and SDB0
- Any “DIR” command emits a FF character at the end (and so scrolls off screen in PuTTY)
My “Set A” RK8E boards
These boards travelled with me to the U.S. in June 2025 and were tested successfully in the test machine at Kyle’s house with my RK05 emulator. However, after returning home, I can’t get this set to work in either my 8/e or 8/f (even though Set B works fine in both machines).
Here is the printout from DHRKBG. The fault occurs about 2 mins 20 seconds into the test:
.RUN RXA1 DHRKBG.SV RK8E DRIVE CONTROL TEST TEST (Y=YES OR N=NO): DISK0?Y DISK1?N DISK2?N DISK3?N SR= 0000 DISK DATA ERROR PC:1172 GD:2525 ST:4000 CM:1000 DA:0000 CA:7177 AD:7201 DT:0525 DHRKBF FAILED PC:5344 AC:0000 MQ:7777 FL:0000 WAITING ^E DISK DATA ERROR PC:1172 GD:2525 ST:4000 CM:1000 DA:0000 CA:7177 AD:7201 DT:0525 DHRKBF FAILED PC:5344 AC:0000 MQ:7777 FL:0000 WAITING ^E DISK DATA ERROR PC:1172 GD:2525 ST:4000 CM:1000 DA:0000 CA:7177 AD:7201 DT:0525 DHRKBF FAILED PC:5344 AC:0000 MQ:7777 FL:0000 WAITING ^E DISK DATA ERROR PC:1172 GD:2525 ST:4000 CM:1000 DA:0000 CA:7177 AD:7201 DT:0525 DHRKBF FAILED PC:5344 AC:0000 MQ:7777 FL:0000 WAITING ^C
It could be that the “Set A” boards will work with a real RK05. I need to wait until I’ve built up Vince’s M883 paddle board and cable set, to try this out.
Resources
Here’s some links that are relevant to the RK05 emulator: