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HP 42S: Difference between revisions
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There are three major revisions of HP 42s: A, B and C respectively. Revision A and B have a plastic pane in front of the LCD whereas revision C has a recessed LCD display. Revision C is the most commonly seen variant today. | There are three major revisions of HP 42s: A, B and C respectively. Revision A and B have a plastic pane in front of the LCD whereas revision C has a recessed LCD display. Revision C is the most commonly seen variant today. | ||
HP 42s used a silicon-on-sapphire [[HP Saturn|Saturn]] architecture chip code-named "Lewis" with 64KB of integral ROM and a RAM controller capable of addressing up to 32KB of memory, driving a 131x16 dot matrix display. 8KB of SRAM is soldered on board and roughly 7000 Bytes are available to the user as program steps or registers. | HP 42s used a silicon-on-sapphire [[HP Saturn|Saturn]] architecture chip code-named "Lewis" with 64KB of integral ROM and a RAM controller capable of addressing up to 32KB of memory, driving a 131x16 dot matrix display. Driven by a bus frequency of 32.768KHz, they are internally stepped up to 1MHz. 8KB of SRAM is soldered on board and roughly 7000 Bytes are available to the user as program steps or registers. | ||
Internally, the HP 42s is extremely similar to both the [[HP 17B|HP 17B & BII]], and [[HP 27S]], with the exception of the lack of an extended ROM chip which on the 17 series contained international language & error message and on the HP 27S contained additional instructions. On the HP 42s, this position remains unsoldered. However, the instruction to jump to this memory location is still retained. | Internally, the HP 42s is extremely similar to both the [[HP 17B|HP 17B & BII]], and [[HP 27S]], with the exception of the lack of an extended ROM chip which on the 17 series contained international language & error message and on the HP 27S contained additional instructions. On the HP 42s, this position remains unsoldered. However, the instruction to jump to this memory location is still retained. | ||
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== Hardware Mods == | == Hardware Mods == | ||
[http://www.finetune.co.jp/~lyuka/interests/calc/hp42s/ Some users] have reported success replacing the RAM chip of their HP 42s with up to 32KB of RAM and modifying the LC circuit to force the chip to run at twice and even quadruple the clock speed. However it must be noted due to the construction of Pioneers calculators, opening a HP 42s involves drilling heat-stakes and thus will irreversibly reduce its structural integrity. | [http://www.finetune.co.jp/~lyuka/interests/calc/hp42s/ Some users] have reported success replacing the RAM chip of their HP 42s with up to 32KB of RAM and modifying the LC circuit to force the chip to run at twice and even quadruple the clock speed, approaching the performance of later Clarke and Yorke architectures. Stable operations at high frequency would require using higher-voltage silver oxide batteries. | ||
However it must be noted due to the construction of Pioneers calculators, opening a HP 42s involves drilling heat-stakes and thus will irreversibly reduce its structural integrity. | |||
== Tricks == | == Tricks == | ||