EBTKS Getting Started

What’s in the box

Depending on how you ordered your EBTKS, it is supplied as just the assembled Printed Circuit Board (PCB) or the PCB with Guide Rails attached


EBTKS without Guide Rails


EBTKS with Guide Rails

Guide Rails

PVC or HDPE plastic guide rails are CNC machined out of gray PVC type 1 or black HDPE. The left and right guide rails are sized to match the guide slots in the backplane of your Series80 computer. These come standard with your EBTKS. They are easily removed if you want to use a 3D printed case.


Left Guide Rail


Both Guide Rails

3D Printed Case

The design files for a 3D printed case are now available on this page. Getting the case printed will be your responsibility, the EBTKS team does not provide these cases

There will be a 16 GB MicroSD Card preloaded with software installed in the Teensy 4.1 module. In case you may want to do additional development on the Teensy module, or maybe remove it from EBTKS to use in another project, the standard Teensy 4.1 reference card is included. If you do unplug the Teensy module (never needed for normal EBTKS use), do it very carefully by slowly levering up each end of the module with a plastic tool, to avoid damaging the module and the PCB beneath it. The pins on the Teensy 4.1 module are very thin and easily bent or broken.

EBTKS is Pre Configured

Based on information you provided at the time of your order, EBTKS has been preconfigured to match your system. This is done with the CONFIG.TXT file which you can edit to change configurations. Please note that this file has a very specific format, and if you edit it, you must verify that you do not mess up the formatting. On the just referenced page, there is information about a syntax checker that is easy to use, to check your changes. There are no user jumpers on EBTKS, every configuration option is controlled by CONFIG.TXT, which is located in the root directory of the MicroSD Card.


MicroSD Card Directory Tree


MicroSD Card Root Directory

Moving EBTKS to a different computer

In the root directory, as well as the CONFIG.TXT file, there are 6 other configuration files, with hopefully informative names. If you want to change the computer your EBTKS is plugged into another computer that is not the same model and same configuration, the CONFIG.TXT file will need to be changed to match the new computer. The easiest way to do this is to delete the CONFIG.TXT file, and make a copy of one of the other 6 files, naming the copy CONFIG.TXT. You should never edit these 6 files, only copies of them. If you do mess things up, you can always get a pristine copy of the MicroSD Card image from the Download page

Time to start playing

(All of the following assumes the standard MicroSD Card file set. The example screen displays are from a HP85B.)

EBTKS is preconfigured to provide 5 floppy disk drives and one 5 MB Winchester drive (all emulated, the actual storage is files on the MicroSD Card).

When you start your computer with EBTKS for the first time, it will show the following two screens (the second one by using the Shift-Roll to scroll up)


First page


Second page

These two pages show how the CONFIG.TXT file was processed as the system started, and you should review the display carefully if you make any changes to CONFIG.TXT . Briefly it shows the following

  • Starting on the first page above, for which model of Series80 computer the CONFIG.TXT file is configured.

  • Whether emulation of the tape drive is enabled (the original goal of EBTKS). Note that for tape drive emulation to work correctly, the physical tape drive must be disabled by unplugging the two flat flex cables.

  • Whether EBTKS provides extended memory, and how much

  • Whether ROMs are loaded for HP85 (or 83 or 9915) or for HP86/87

  • Which ROMs are enabled

  • Seen on the second page above, the association between Mass Storage Unit Specifiers (abbreviated in HP Mass Storage Manual as msus) and the files that store the Floppy or Winchester disk image.

This startup display can be disabled in the CONFIG.TXT file by changing the line:

"CRTVerbose": true,
"CRTVerbose": false,

The disk image file associated with msus 300 is the initial default Mass Storage device (in the EBTKS situation, an emulated device), which is shown on the second page above is /disks/EBTKS_1.0_85.dsk

Typing CAT will list the contents of this emulated floppy disk (/disks/EBTKS_1.0_85.dsk)


Catalog of msus 300

Some of these programs will run without problems, and some will need editing to match your computer’s configuration

Here are some simple examples:

The DATE program retrieves the current time and date from the on-board battery backed up clock. It is set to California time, PDT time zone. It uses a new keyword DATETIME . LIST the program to see how it works.


The DATE Program

The DF program shows the amount of total unused disk space and the largest unused space. (in a PACKed disk, these are the same). This is an example of a program that needs to be edited depending on your system. On an HP85B, which always has at least a small EDISK, no editing is needed. On all other systems, if there is no EDISK, line 110 must be changed as shown in the third image below.


The DF Program (Disk free space)


Running DF on an HP85B


Running DF on an HP85A, after editing of line 110

The SINE program is as boring as you would expect it to be, and is not worthy of a screen capture.

The programs are used to test the two RGB LEDs on the back edge of EBTKS.
You can turn the LEDs off with SETLED 3,0,0,0


Two disk speed benchmarking programs

RWBENCH85B  (this can also be used on HP86 and HP87)

were used to get the performance data presented at the end of this forum article . The program will probably need editing depending on whether you have EDISK enabled, and whether you have an HP9121 floppy disk drive attached via an HPIB interface with a msus of 700

The EBTKS-TEST program checks multiple parts of EBTKS, and does not need any editing. On an HP85B it takes about 45 seconds to run. Here are the expected two screen pages:


Running EBTKS-TEST on an HP85B, page 1


Running EBTKS-TEST on an HP85B, page 2

Pressing CONT will repeat the test and increment the PASS count.

What else is on the MicroSD Card

The Directory Tree diagram near the top of this page shows many directories.
This is documented in detail here A Guided tour of the MicroSD Card

Here is a brief summary.


covered above


BASIC programs in ASCII source form.
SDSAVE /BAS/DF.BAS stores the DF program in source form
SDGET /BAS/DF.BAS loads the source file DF.BAS
If these .BAS files are transferred to a PC, they can be edited with a text editor


This is where the disk image files reside


This is a copy of all the disk images found in Everett Kaser’s Series80 emulator


All the help text for HP85A/B are in this subtree. This is still a work in progress


All the help text for HP86A/B and 87/87XM are in this subtree. This is still a work in progress


Disk and tape images of blank media. Used when creating a new Disk or Tape


Output that would normally go to the printer can be redirected to a file in this directory


All of the available ROMs compatible with HP85A/B


All of the available ROMs compatible with HP86A/B and HP87/87XM


This is where the tape image files reside. unused on HP86A/B and 87/87XM


A test directory used during development, and by EBTKS-TEST


BASIC programs in tokenized form. Functionally the same as saved programs in the emulated disks.
SDLOAD /TOK/DF.TOK loads the DF program.
SDSTORE /TOK/DF.TOK saves the DF program in tokenized form.

EBTKS Configuration

The checklist page that is included with your EBTKS lists the initial settings for your EBTKS. These are included in the CONFIG.TXT file that is in the root directory of the provided SD Card.
See Working with CONFIG.TXT for details of how to make changes to this file.
The checklist also lists the expected configuration of your system, with regard to the following:

  • Is the tape drive connected (for HP85A and HP85B)

  • It is expected that there is no ROM module or other ROM card installed as EBTKS should be able to provide all the ROMs you need

  • On HP85A, don’t install an extra 16 kb memory module as EBTKS can provide this memory.

  • On HP85B, EMC memory modules can be used for EDisk. See EMC for details.

  • Typically, a HP85B has 3 option ROMs pre-installed on the main board:

    • I/O                     (Octal 300 )

    • Mass Storage    (Octal 320)

    • EDisk                 (Octal 321)

    Do not enable these ROMs on EBTKS on an HP85B system, as it will cause incorrect operation.
    A similar constraint exists for HP86A/B and HP87/87XM pre-installed ROMs.

  • EBTKS uses module select code 3 for an emulated HPIB interface that is the gateway to emulated floppy disk drives and emulated hard disk drives. It is also used for an emulated printer Therefore, if you have a real HPIB interface module plugged in for

    • Other real disk drives

    • Test and Measurement equipment

    • Data acquisition

    • Printers

    • Plotters

    • Emulated disks that connect over real HPIB

    the real HPIB interface must not use select code 3. By default, HP ships HPIB interface modules with select code 7.

As you will see on the Working with CONFIG.TXT page you can make edits to the file by putting the SD Card into a PC and using a simple text editor like notepad.

This allows changing the initial disk and tape drive assignments to various LIF image files. Even though it looks like you can add new additional sections following the existing format, please don’t, as things will probably break. At a later time, hopefully an EBTKS owner will write a utility program that runs on the HP85 and automates simple changes to the CONFIG.TXT file.


CONFIG.TXT is an ASCII text file in JSON format. Editors like WordPad and MSWord add additional information like character height, font selection, and other formatting control. This will corrupt the file.
While Notepad can be used for editing CONFIG.TXT, another far superior free editor that does not add formatting is Notepad++ which can be found with Google Search.
For Linux/Unix systems, suitable editors include VI, VIM, EMACS, Nano, Atom, Gedit.

A few New Keywords

The following are useful initial keywords to check the firmware and AUXROM versions, and which ROMs have been loaded. These are all just typed at the BASIC prompt. See AUXROM Keywords for the full list of over 57 new keywords, with more detailed explanations and examples


Returns the AUX ROMs revision# (from ROM 361)


Returns a string containing date and time of building the EBTKS firmware


Displays all the possible ROMs for HP85/86/87 and their Octal/Decimal ID number


Displays currently installed ROMs and their Octal/Decimal ID number. AUXROMS are loaded as a set with Octal IDs 361, 362, 363, 364. LISTROMS will only list the first one

Connecting the serial diagnostic port


There are several help pages that list the available commands. Just type the number 0 to 6 and enter to get a short help page.

The serial diagnostic port Help

This section of EBTKS is likely to change since it is primarily a debug tool for the EBTKS developers

Here are the 7 pages of help


EBTKS Control commands - not case-sensitive

0     Help for the help levels
1     Help for Display Information
2     Help for Diagnostic commands
3     Help for Directory and Time/Date Commands
5     Help for Developers
6     Help for Demo
Commands to Display Information
show -----    Show commands have a parameter after exactly 1 space
     log      Show the System Logfile
     boot     Show the messages from the boot process, sent to Serial port
     CRTboot  Show the messages sent to the CRT at startup
     config   Show the CONFIG.TXT file
     media    Show the Disk and Tape assignments
     mb       Display current mailboxes and related data
     CRTVis   Show what is visible on the CRT
     CRTAll   Show all of the CRT ALPHA memory
     key85_O  Display HP85 Special Keys in Octal
     key85_D  Display HP85 Special Keys in Decimal
     key87_O  Display HP87 Special Keys in Octal
     key87_D  Display HP87 Special Keys in Decimal
     other    Anything else is a file name path
Commands for Diagnostic
la setup      Set up the logic analyzer
la go         Start the logic analyzer
addr          Instantly show where HP85 is executing
kbdcode       Show key codes for next 10 characters in the keyboard byffer
clean log     Clean the Logfile on the SD Card
sdreadtimer   Test Reading with different start positions
SDCID         Display the CID information for the SD Card
PSRAMTest     Test the 8 MB PSRAM. You probably should do the PWO command when test has finished
ESP32 Prog    Activate a passthrough serial path to program the ESP32
pwo           Pulse PWO, resetting HP85 and EBTKS
Directory and Date/Time Commands
dir tapes     Directory of available tapes
dir disks     Directory of available disks
dir roms      Directory of available ROMs
dir root      Directory of available ROMs
Date          Show current Date and Time
SetDate       Set the Date in MM/DD/YYYY format
SetTime       Set the Time in HH:MM 24 hour format
adj min       The U and D command will adjust minutes
adj hour      The U and D command will adjust houres
U             Increment the time by 1 minute or hour
D             Decrement the time by 1 minute or hour
Commands for Auxiliary programs
Commands for Developers (mostly Philip)
crt 1         Try and understand CRT Busy status timing
crt 2         Fast CRT Write Experiments
crt 3         Normal CRT Write Experiments
crt 4         Test screen Save and Restore
crt 5         Test writing text to HP86/87 CRT
Commands for Demo
graphics test  Set graphics mode first
jay pi         Jay's Pi calculator running on Teensy

Boot logging

Every time EBTKS starts up it creates three logs.

  • Short list of ROM and Disk Mounts can be sent to the CRT. Can be disabled in CONFIG.TXT from being displayed

  • A detailed report on the processing of the CONFIG.TXT file. Always sent to the serial diagnostic port.

  • A similar report to the report that is sent to the serial diagnostic port, is appended to a log file on the MicroSD Card