For authentic PDP-1 software, start with the Computer History Museum (CHM) for historical context and archival catalog records, then use the MAME guide or SIMH manual to find an emulator route and load compatible digital paper-tape images. A catalog entry is a discovery lead—not proof that a file’s contents match the original tape. The available sources do not establish file hashes or independent verification of individual images.
Where to find PDP-1 software
Use the Computer History Museum for provenance and discovery
The CHM PDP-1 software page explains that most PDP-1 software was released on paper tape and describes the restoration team’s use of copies to avoid risking original tapes. Its PDP-1 archival finding aid describes the collection and directs readers to the Museum’s catalog for paper-tape records. The finding aid reports 388 software paper-tape catalog records.
That number refers to catalog records, not 388 machine-verified files. CHM says the descriptions were transcribed from what was written on the tape; the tapes were not machine-read to verify their contents. Use a record to identify a candidate program and seek corroborating documentation before treating a digital image as authentic.
Find digital tape images through the MAME guide
The MAME Developer Wiki’s PDP-1 guide links a digital paper-tape software archive and documents a Spacewar example. It is a practical starting point when you want an image associated with MAME, but the guide does not establish the integrity or current availability of every file in the archive.
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Choose an emulator route
MAME and SIMH document different ways to approach PDP-1 software. The sources do not establish a universal winner or provide current operating-system-by-operating-system comparisons. Choose based on whether the program is available in the associated image set, whether its tape format is supported, and what device behavior the program needs.
| Route | What the documentation provides | What to check |
|---|---|---|
| MAME | The PDP-1 guide documents launching the system with mame pdp1, links a paper-tape software archive, and gives a Spacewar example. |
Confirm the desired image is available and follow the guide’s reader interaction. MAME notes that emulation may lack something needed for some programs to work perfectly. |
| SIMH | The SIMH PDP-1 Simulator Usage manual documents tape loading, RIM and BLK formats, and simulated PDP-1 devices. | Match the image format to the loader and consider whether the program depends on devices or behavior the simulator supports. |
Running the MAME Spacewar example
The MAME guide gives mame pdp1 spacewar as its Spacewar example, followed by an action using the paper-tape reader. Consult the guide for the documented interaction sequence. This is a documented route, not a claim that the example or archive was tested here.
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Loading a tape image in SIMH
SIMH’s manual documents LOAD for RIM- and BLK-format tapes. It assumes .BIN files are BLK unless otherwise directed; other files default to RIM. Its examples include LOAD lisp.rim and LOAD -B macro.blk. Use the command that matches the actual image format; changing a file extension does not convert its contents.
How to assess a tape image
There is no single check in these sources that proves an individual download is an exact copy of a historical paper tape. Assess confidence by combining catalog information, documentation, format compatibility, and documented load behavior.
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- Identify the program. Compare the catalog description and tape-label information with the program name and any available documentation.
- Look for corroboration. Check whether the image is listed in the MAME guide’s software archive or supported by other program documentation. A catalog record alone does not verify bytes or contents.
- Check the format. Determine whether the image is RIM or BLK before using SIMH’s
LOADcommand. Do not infer format solely from a renamed extension. - Follow the emulator’s documented procedure. A successful load is useful evidence that the image and emulator can work together, but it is not proof that the file is an exact archival copy.
- Interpret failures cautiously. MAME warns that its emulation may be missing something required by some programs. A failed launch alone does not show that the tape image is corrupt.
The sources do not provide independent checksums for the archive files or a comparison between a downloaded image and an original tape. Treat authenticity as unconfirmed unless you find evidence beyond the catalog description and emulator behavior.
What the PDP-1 collection includes
CHM’s PDP-1 specifications page lists an 18-bit word length and 28 single-address instructions. The archival finding aid describes material spanning 1959–1976 and includes manuals such as a 1963 PDP-1 Handbook. These details can help identify historical context, but they do not authenticate a particular software image.
Version and date context
The MAME PDP-1 guide was last modified on 2023-02-20. The SIMH manual is dated 2008-12-01. A SIMH repository announcement identifies v3.12-3 as the then-current official version on 2022-12-12; that dated statement does not establish which version is latest in 2026. Check the relevant project documentation for current release information before downloading or installing an emulator.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.License note for SIMH
The SIMH PDP-1 manual includes a permissive license notice that allows use, copying, modification, distribution, and other activities subject to its stated conditions. If you distribute copies or substantial portions of the software, preserve the applicable notice and conditions. Consult the manual for the full license text.
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