PS1:PS1 Model Differences

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Page content & researching collaboratively taken from io55.net's PS1 page and albalog.blog.hu's posts (specific pages in references) with permission.

There are three PS1 models, with the original model having five retail revisions.

Models + Revisions

Models are arranged chronologically. Revisions are underneath their respective model.

“PlayStation (original)” (1995-2000)

The instantly recognizable “fat” gray console. Various revisions exist within this version, all of which change something about the console's I/O or internals. Up front is 2 controller ports and 2 memory card ports. On the top is the CD drive with the buttons for power, reset, and opening the drive. To the back is the aforementioned I/O, which always has AC power, multi video out, and serial I/O. Older revisions will have direct RCA + RFU out and/or parallel I/O. Furthermore, some older revisions have technical and graphical issues or inferiority. Reliability is mixed across all revisions, with some faring worse than others. This version is the most commonly model found for the PlayStation.

“SCPH-100x” (1995-1997)

The first PlayStation, possessing the most ports; direct RCA + RFU in addition to parallel/serial/etc. Alongside that, the CD tray has the laser/”black” area up top, instead of to the right. Due to a poor CD drive laser, these consoles experience FMV and music skipping in games at a notorious level. Paradoxically, the DAC in these systems made them favorable for music CD playback, supposedly on par with the best CD players of their era, not ours (202X).

These systems have two variants of the motherboard, one is known as the PU-7 (made early November 1995 and prior), while the other is known as the PU-8 (made late November 1995 and after). For units with a label batch of November 1995, the motherboard needs to be examined manually to determine if it is a PU-7 or a PU-8. The PU-7 motherboards use outdated VRAM, resulting in lower (5-bit) shading + worse transparency blending. This leads to both slowdowns (transparency) and color banding (shading). However, the PU-8 motherboards are updated to use SGRAM, allowing the console to support 8-bit shading, in addition to swifter transparency calculations and full screen dithering. In essence, this system's high point is the direct RCA/RFU + high quality DAC. Examples of these differences can be found on the Video Output Notes page.

Batches of the 100x were manufactured from July 1995 to April 1997, being made in either Japan or (in rare cases) the United States. These models are compatible with xStation and PSIO.

“SCPH-550x” (1997-1998)

Here, the direct RCA and RFU have been removed from the console (still possible to attain RCA with a multi out to RCA cable), and uses the PU-18 motherboard. The DAC has been downgraded, but all models use the updated SGRAM. Lastly, the drive lasers have been improved somewhat, eliminating the notorious level of skipping found in the 1001. As with all PS1s, however, the drives still can have their issues, just not as badly as the 1001. Some claim these have the highest quality video output, but this is unverified and needs investigation. Note: SCPH-5001 does not appear to have been manufactured at any point, and thus it has been excluded.

Batches of the 550x were manufactured from May 1997 to April 1998, being made in either Japan or Mexico. These models are compatible with xStation and PSIO.

“SCPH-5903” (1995-1996?)

Included for it’s especially interesting featureset, even if it's an NTSC-J revision. Exclusive to southeast Asian markets, this revision has reintroduced the direct RCA and RFU, while also adding Video CD support (which was originally planned worldwide). These also use the revised board which contains SGRAM over VRAM, and potentially the better laser. The quality of their DAC is unknown.

“SCPH-700x/750x” (1998-1999)

These systems contain a smaller and more efficient motherboard with less chips, which impacts the user if they are interested in hardware modding. Since the CD DSP is now merged with another CD chip, installing the xStation drive emulator has been rendered impossible, except for certain early 7000s with a PU-18 motherboard. However, one can still install the PSIO drive emulator despite this change. These systems also have a music visualizer, and were the first systems to be bundled with the DualShock controllers. Some claim that the 750x have the best and clearest video output, in direct opposition to the 550x and the 700x. That, like the 550x's claim, is equally unverifiable and needs investigation.

Some 750x units made in April and May 1999 have a 900x shell, with no cutout for the parallel port despite the motherboard having the port. Likely, this was the timeframe when Sony was concerned about the parallel port being used for piracy concerns, considering that a month earlier in March 1999, the Bleem! emulator was publicly released.

Batches of the 700x were manufactured from April 1998 to August 1998, being made in either Japan or Mexico. Most of them use a PU-20 motherboard. Those are capable of PSIO, but not xStation.

Batches of the 750x were manufactured from August 1998 to May 1999, being made in either Japan or Mexico. Most of them use a PU-22 motherboard. Those are capable of PSIO, but not xStation. Very few 750x units use a PU-20 or even a PU-18.

“SCPH-900x” (1999-2000)

These systems have continued the trend of shrinking the motherboard and reducing the chips, with a more immediate detriment to user. Alongside not supporting the xStation, these consoles do not have a parallel port (or simply no cutout for it). Simultaneously, they don’t bring any upgrades to the table, for either the laser or the hardware.

It is important to note that some earlier 900xs, in particular for some units that were made in May 1999, actually have a PU-22 motherboard with a parallel port, but it is covered up by the console’s case. These were most likely 750xs that was mislabeled as a 900xs. This lack of the visible parallel port makes using the PSIO either very difficult or impossible, unless the 900x console shell is replaced with a 550x, 700x or 750x shell.

Later 900xs made June 1999 and after do not have a hidden parallel port.

Batches of the 900x were manufactured from May 1999 to August 2000, being made in either Japan, Mexico, or (for some very late units) China. Most of them use a PU-23 motherboard, which is not compatible with either xStation or PSIO.

“Net Yaroze (DTL-H300x)” (1997-2000?)

A slightly different variant of the standard PS1, intended for indie developers and hobbyists. Despite this status, almost nothing is changed in the console’s hardware, although it is black in color. The only meaningful changes are the lack of region lockout & the different boot ROM. Everything else of note relates to the extras the system shipped with. The one other upside is that the Yaroze has direct RCA + RFU out, whilst also seemingly containing the superior SGRAM (possibly the better laser too, some disagree). This makes the Yaroze the only consumer-level PS1 that has both the direct RCA out and the SGRAM.

“PS one (SCPH-10x)” (2000-2004?)

A cost-reduced and shrunken version of the PS1, colored in white with a rounded design. About as common as the "fat" PS1. The I/O of this console is even more reduced than the last revisions of the "fat", as the PS one does not have an accessible serial port or a reset button. However, significant modding allows re-adding the serial port to the PS one system. Lastly, the PS ones appear to have some of the best reliability compared to earlier models.

Batches for North America were produced from August 2000 to the fourth quarter of 2004 (date code of "4D"), being made in China or (for some early units) Japan. Like the 900x, PSones are not compatible with either xStation or PSIO.

The 2006 discontinuation date seems to be either de-jure, or the discontinuation year in Japan and PAL countries.

Sony's official reports list North American sales not changing December 31, 2004, which corresponds with the "4D" date code. In Japan and Europe, the reports show that sales didn't change after March 31, 2005, which was most likely the point when the fourth quarter of 2004 batch ran out in those regions. However, Sony de-jure announced the PS one's discontinuation on March 23, 2006, despite conflicting with Sony's official sale press releases and the labels found on PS one models.

Region Codes

The PlayStation only has 4 region codes. The end digit in the model number indicates the console's region. More detailed information on the PlayStation's region differences can be found here.

  • 0 is Japan (Japanese boot ROM, NTSC:J region, NTSC Video, 100 V PSU)
  • 1 is USA/Canada (English boot ROM, NTSC:U/C region, NTSC Video, 110 V PSU)
  • 2 is Europe/Australia/PAL region (English boot ROM, PAL region, PAL Video, 220-240 V PSU)
  • 3 is Asia (English boot ROM, NTSC:J region, NTSC video, Wide range 110-240 V PSU)

References

https://en.wikipedia.org/wiki/Net_Yaroze

https://www.retrorgb.com/playstation1.html

https://en.wikipedia.org/wiki/PlayStation_models

http://www.psxdev.net/forum/viewtopic.php?t=365 (ps one serial mod)

https://gametrog.com/playstation-1-one-information-specs-versions/

https://reddit.com/r/psx/comments/ie0xqr/question_for_scph5001_owners/

https://segaretro.org/Sega_Saturn/Hardware_comparison#Revised_PlayStation (SGRAM again)

https://albalog.blog.hu/2023/10/07/ps1_modell_gyujtemeny_datum_szerint (PS1 fat batch production dates)

https://albalog.blog.hu/2023/11/06/ps1_modell_gyujtemeny_gyartasi_orszag_szerint (PS1 fat countries of manufacture)

https://albalog.blog.hu/2024/01/16/psone_slim_orszagok_es_datuminformaciok (PSone batch production dates & countries of manufacture)

https://www.reddit.com/r/psx/comments/113mrow/ps1_model_buying_guide_perhaps_the_most_reliable/ (other info)

https://web.archive.org/web/20110524023857/http://www.scei.co.jp/corporate/data/bizdataps_e.html (sales info from Sony)

https://www.psdevwiki.com/ps1/Motherboards (motherboard info)