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MPU-401 Age??

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First post, by Artex

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I recently picked up a Roland MPU-401 breakout box, and on the top cover it says "Roland DG." I've seen other Roland MPU-401 boxes like this that just say "Roland" on the top cover, so I'm trying to figure out the difference between the two.

Mine:
dscf0115h.jpg
dscf0112w.jpg

The one on wikipedia just says "Roland" on the top cover & looks like it has two chips missing on the PCB that are present on mine. On mine, The bigger chip says "Roland 1.5 DB" whereas the chip is completely missing from the PCB of the MPU-401 linked here:
Roland_MPU-401.jpg

I know Roland branched off at some point, but I'm just trying to figure out the age of my unit.

Reply 1 of 7, by Cloudschatze

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Yours is an older unit, manufactured in May of 1985. The unit in the Wikipedia photograph (which belongs to me, coincidentally) is of the later variety, with an internal, rather than external, ROM.

Last edited by Cloudschatze on 2013-03-02, 01:26. Edited 1 time in total.

Reply 2 of 7, by Artex

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Cloudschatze wrote:

Yours is an older unit, manufactured in April of 1985. The unit in the Wikipedia photograph (which belongs to me, coincidentally) is of the later variety, with an internal, rather than external, ROM.

Interesting! Is there a way to tell by serial number? Where did you come up with that date?

Reply 5 of 7, by Great Hierophant

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Cloudschatze wrote:

Yours is an older unit, manufactured in May of 1985. The unit in the Wikipedia photograph (which belongs to me, coincidentally) is of the later variety, with an internal, rather than external, ROM.

To clarify what Cloudschatze is trying to say, in your unit you will have a ROM or an EPROM chip where you see the holes on Cloud's board. In his board, the ROM is contained within the large, 40-pin DIP. In both boards, this is the microcontroller, but in Cloud's board the newer chip in addition contains enough ROM space to contain the code for the MPU. I have Cloud's type of MPU as well.

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Reply 6 of 7, by Artex

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Great Hierophant wrote:
Cloudschatze wrote:

Yours is an older unit, manufactured in May of 1985. The unit in the Wikipedia photograph (which belongs to me, coincidentally) is of the later variety, with an internal, rather than external, ROM.

To clarify what Cloudschatze is trying to say, in your unit you will have a ROM or an EPROM chip where you see the holes on Cloud's board. In his board, the ROM is contained within the large, 40-pin DIP. In both boards, this is the microcontroller, but in Cloud's board the newer chip in addition contains enough ROM space to contain the code for the MPU. I have Cloud's type of MPU as well.

Gotcha-

In general, are the units that say Roland DG older than the plain "Roland" branded units? When did they switch?

Reply 7 of 7, by Cloudschatze

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Roland's Second Edition MPU-401 Service Notes, dated Mar. 1986, state that the brand changed from "Roland DG" to "Roland" starting with SN533500 (April, 1985). Based on your serial number, this information is obviously incorrect. A soft transition likely occurred, involving the use of existing stock, etc., and I imagine it is safe to assume that by June of 1985 (if not sooner), all newly produced units were "Roland" branded.

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