Difference between revisions of "UNIBUS boot ROMs"

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DEC produced several generations of '''[[UNIBUS]] [[Read-only memory|ROM]] boot''' cards.
 
DEC produced several generations of '''[[UNIBUS]] [[Read-only memory|ROM]] boot''' cards.
  
The first was the [[BM792 ROM]] card, which used individual diodes in an array to represent individual bits; it contained only 32 words of memory. The second was the [[M9301 ROM]] card; it had a capacity of 512 words, using [[PROM]] chips. The third was the [[M9312 ROM]] card, which also had a capacity of 512 words.
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* The first was the [[BM792 ROM]] [[DEC card form factor‎|quad]] card, which plugged into an [[Small Peripheral Controller|SPC]] slot; it used individual diodes in an array to represent individual bits, and contained only 32 words of memory.
  
In both of the latter two cards, the entire ROM contents were directly visible on the UNIBUS, not through a window.
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* The second was the [[BM873 ROM]], also a quad card used in an SPC slot; it contains 128 words, using 2 [[PROM]] chips.
  
There was also another early [[DEC card form factor‎|quad]] ROM card, the [[M873 ROM]], but almost next to nothing is currently known about it; apparently it contains 128 words, using 2 of the ROM chips like those in the M9301.
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* The third was the [[M9301 ROM]] card, a dual card intended for use in the top two rows of a [[Modified UNIBUS Device|MUD]] slot; it had a capacity of 512 words, using four chips like those in the BM873.
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* The last was the [[M9312 ROM]] card, which also had a capacity of 512 words.
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In both of the latter two cards, the entire ROM contents were directly visible on the UNIBUS, not through a window, unlike later, larger [[QBUS]] ROM cards.
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[[Category: UNIBUS ROMs]]

Latest revision as of 00:12, 17 December 2018

DEC produced several generations of UNIBUS ROM boot cards.

  • The first was the BM792 ROM quad card, which plugged into an SPC slot; it used individual diodes in an array to represent individual bits, and contained only 32 words of memory.
  • The second was the BM873 ROM, also a quad card used in an SPC slot; it contains 128 words, using 2 PROM chips.
  • The third was the M9301 ROM card, a dual card intended for use in the top two rows of a MUD slot; it had a capacity of 512 words, using four chips like those in the BM873.
  • The last was the M9312 ROM card, which also had a capacity of 512 words.

In both of the latter two cards, the entire ROM contents were directly visible on the UNIBUS, not through a window, unlike later, larger QBUS ROM cards.