Tandem Computers Inc reports that PCs Limited in Dallas has put in its second NonStop system under a plan to integrate all operations of the rock-bottom mail-order Personalike marketer, including order management, manufacturing and financial accounting, on Tandem computer systems by late this year: the $560,000 NonStop TXP system will handle general ledger, accounts receivable, accounts payable and fixed assets when it goes on-line, due to happen next month.